(In a trial held after his father, George, was re-captured, George Latimer was represented by Frederick Douglass and William Lloyd Garrison, the famed abolitionists.) Lewis Latimer had little access to formal education, but after serving several years on a Union gunship during the Civil War—he joined at age 15—he got hired by the patent firm here at a salary of $3 per week, and taught himself how to draft intricate and detailed mechanical drawings. He rose to become head draftsman at the firm. Latimer helped the inventor of the telephone, Alexander Graham Bell, create the drawings used for the telephone’s first patent filing, and later, he worked with other inventors, including Hiram Maxim and Thomas Edison, to extend the useful life of the light bulb from minutes to hours and make it easier to manufacture, filing several patents of his own. By the end of Latimer’s career, he was a member of the Edison Pioneers, a small group of people who had worked closely with Edison in the early stages of his career. He was the only Black person in that group.

On your way to the next stop, see if you can spot a statue of Ben Franklin, the prolific inventor and signer of the Declaration of Independence. He attended Boston Latin School, originally located on this site, but ended his formal schooling at age 10 to work in his father’s soap and candle making shop not far from here. Boston Latin was America’s first public school, founded in 1635, offering free tuition to its students of all classes. It still exists, although in a different location.

Two of the founders had graduated from MIT—then called “The Tech”—so the name of their company is a reference to their alma mater. They set up a film processing lab in a railroad car, hitched it to a train, and sent it to Jacksonville, Florida, to shoot the first Technicolor film, “The Gulf Between.” It was shown for the first time here in 1917, and shortly after in New York—mainly to try to interest movie producers and theater owners in the idea of color movies. As the movie industry gravitated to Los Angeles, Technicolor followed it, leaving Boston behind. While you would have been among the first people to see a color movie if you were here in 1917, it wasn’t until 1939—the year that “Gone with the Wind” and “The Wizard of Oz” were made—that Technicolor convinced the movie industry that color was here to stay.

On the way to your next stop is the Omni Parker House Hotel, where both Boston Creme Pies and Parker House Rolls were invented.

Part of Tudor’s genius was in selling a product that was free—frozen pond water—and using another free product—sawdust—to insulate it when he packed it into sailing ships and sent it around the world. (He tested various ways to keep the ice cold in transit and in storage at its ultimate destination.) Tudor’s ice made it to the Caribbean, India, Hong Kong, and England, and he built a network of ice houses around the world to store it. In warm weather countries like Cuba and Martinique, Tudor’s ice was used to make ice cream for the first time.

He would tell his salesmen to give bartenders a free one-year’s supply, after teaching them to make cocktails that benefitted from having ice in them. That created loyal customers. (Year-round access to ice was also helpful to doctors, who used it to treat patients who were suffering from severe fevers.) Along the way, Tudor went bankrupt and served time in debtor’s prison. But he eventually succeeded and became known as “The Ice King.” He died in 1864 in his home on Beacon Hill, and is buried in the back right corner of this cemetery. Look for a small, faded tombstone that says John Tudor, and an explanatory sign nearby.

There’s not much trace of him—or Cotton Mather’s house, which was located near Hanover Street, the neighborhood’s main street. Onesmus was born in the late 1600s, and lived in Mather’s household in the early 1700s. One of the most feared diseases of the time was smallpox, which killed about 30 percent of the people who got it, and left many of the survivors with severe scars—pockmarks—on their faces. Onesimus explained to Mather that in Africa, he had been inoculated against smallpox. His arm was cut open, a small amount of material from a person infected with smallpox was inserted into the wound.

Though Mather tried to promote the idea of inoculation as a smallpox epidemic gripped Boston in 1721, people at the time were skeptical of a medical procedure that seemed to be based on African customs. (At one point, someone hostile to the idea threw a small bomb through Mather’s window—which luckily failed to explode.) But Mather and a doctor who lived near present-day Government Center, Zabdiel Boylston, gathered data about the survival rates of those Bostonians who were inoculated. In the 1721 smallpox outbreak, only two percent of inoculated people died, compared to almost 15 percent of those who had not been inoculated. This was one of the earliest clinical trials on record in the US, using experimental and control groups to illustrate the effectiveness of inoculation. It would not have been possible without Onesimus.

After the telegraph had been developed in the 1830s and begun to be used as the first real-time, long-distance communications technology, inventors began thinking about how to improve it. Maybe you could send multiple signals down the same wire, or perhaps even a human voice? The telegraph shop run by Charles Williams, Jr. was a magnet for telegraph tinkerers—including a young telegraph operator who worked for Western Union named Thomas Edison, who hung out after work in this shop.

Edison’s first patented invention, an automatic vote-recording machine for Congress and other legislative bodies to use when taking votes, was a flop, but it taught him an important lesson. Elected officials didn’t want to make vote counting faster, because then there was less time to convince their fellow legislators to change their votes. After that, Edison resolved that he would only invent things that people wanted.

But a Boston University professor named Alexander Graham Bell invented something pretty successful here: the telephone. Williams liked the invention, and had the first two telephones installed in his shop and his home in Somerville three miles away (which is still standing, at 1 Arlington Street, Somerville.) His phone numbers? 1 and 2. In the first few years after the telephone’s invention, every piece of telephone equipment was made in this building—until demand got too great.

Why did Bell, who was born in Scotland, went to college in London, and lived much of his life in Canada, invent the telephone here? He was able to establish a network of skilled technicians, and find an early investor who was the father of one of his students at the then-new Boston University. He had people like Lewis Latimer to help him file patents. Innovations don’t happen without money, networks of people to work with you, and a city that has early adopters like Charles Williams Jr.

The Dome is a top-floor operating theater that was designed to allow doctors and medical students observe surgeries as they happened, and in the years before Edison’s electric light bulb, it relied on the sun and skylights in the roof to provide enough illumination so the surgeons could see what they were doing. In 1845, the head surgeon at Mass General, John Collins Warren, performed a tooth extraction on a medical student using the gas nitrous oxide to knock out the patient. Unfortunately, the dose wasn’t right, and the patient experienced just as much pain as if the gas hadn’t been used.

Warren tried again in 1846, using a different gas, sulfuric ether, and a different person administering it, the Boston dentist William T.G. Morton. This time, after a patient had a tumor from his neck removed, he described the feeling as having his neck scratched a bit. The use of inhaled ether as an anesthetic spread around the world; it allowed surgeons to perform a much wider range of operations without causing pain. Warren was a big deal: he was a founder not only of Mass General Hospital, but also the New England Journal of Medicine, and he served as the first dean of Harvard Medical School. (Warren also is tied to the American Revolution: his father, also a doctor, treated wounded soldiers in the early battles, and his uncle, Joseph Warren, was a leading Patriot who fought and died at the Battle of Bunker Hill in 1775.)

Mass General has been the site of many other firsts, including the first surgery to reattach a limb, in 1962, and the first use of “telemedicine” in 1968 to enable doctors to evaluate and treat patients in another location.

Entrepreneurs helping one another by offering feedback, or connections to potential customers or investors, was a key part of the formula. What started as Cambridge Incubator became Cambridge Innovation Center, and later CIC. Today, the CIC buildings in Kendall may be home to more startups and venture capital firms than any other buildings on the planet. The CIC served as the first Massachusetts address for tech giants like Google, Apple, and Amazon. It was the original address for successful companies like HubSpot, a marketing software company that is now publicly-traded and has an office of its own. CIC now has a global footprint, operating over 1 million square feet of office and lab space in cities like Philadelphia, Rotterdam, Warsaw, and Tokyo. CIC Health, launched during the COVID-19 pandemic, provided testing services to schools, and operated large-scale vaccination clinics at Fenway Park and Gillette Stadium.

Venture Café, another CIC founded entity, hosts public networking events, panel discussions, and pitch nights. Stop by almost any Thursday night of the year to see for yourself.

Just across Broadway from the tower at One Broadway, you'll see a plaza with a globe fountain in the center. Seek out the "Looking Glass" sculpture, designed by teen creatives from the nonprofit Innovators for Purpose. It's a wonderful photo spot that declares Kendall Square is the "most innovative square mile on the planet."

So Boston not only brought the world the telephone in the 19th century, but it also helped to create the world’s most popular smartphone operating system of the 21st century, with more than 2.5 billion Android users. As of 2021, Google’s Cambridge employees were working on projects for youtube, Google Travel, and Google News.

Secret spot: While you can’t go into Google to enjoy their free cafeteria food, snacks, and coffee, you can go up to the Kendall Rooftop Garden, which looks in on some of the Google space. It is being renovated but will open in Summer 2022. It’s a great place for a rest or a picnic lunch.

The creator of the World Wide Web, Tim Berners-Lee, works here—though the web was invented when Berners-Lee worked in Switzerland. The current building was designed by the California architect Frank Gehry, and named for Ray Stata, an MIT alumnus who co-founded the chip company Analog Devices. Bill Gates, the Harvard drop-out who co-founded Microsoft, was also a major donor.

This site was previously home to the Rad Lab, which was set up in the years leading up to World War II to develop key radar technologies. Many historians regard these technologies as crucial to the Allied victory over Hitler, helping the Allies to “see” enemy ships, planes, and other targets at long distances, and better direct their guns and bombs. It was also in this building that the term “hacker” was first used—in a positive context—and many of the origins of hacker culture had their roots, as part of the MIT Model Railroad Club. (Closed to the public during COVID pandemic.)

The Broad Discovery Center has five galleries where visitors can immerse themselves in interactive and informative exhibits. Visitors learn how researchers at Broad and its partner institutions are teaming up with collaborators across the globe to chase down the roots of psychiatric conditions, cancer, infectious diseases, and more, develop new strategies for treatment, and build datasets and technologies to share with other scientists.

Optional stop: Directly across the street is the Koch Institute for Integrative Cancer Research (500 Main Street), which has public galleries that are accessible on weekdays. These feature scientific photography and art, and provide an overview of current cancer research at MIT.

When the Human Genome Project was seeking to map the entire human genome—described as the world’s largest collaborative biological project—the Whitehead was the single largest contributor. The Whitehead’s Center for Genomic Research was spun out in the early 2000s to create the neighboring Broad Institute. Groups at the Whitehead are currently seeking to understand the biology of infectious diseases; why cancer cells behave differently from healthy cells, and what enables them to multiply so quickly; new ways to model and understand how the brain works; and many other biological domains.

Biogen’s mastery of recombinant DNA technology—using enzymes to “cut and paste” sequences of DNA to achieve therapeutic effects—enabled it to develop a vaccine for hepatitis B, as well as the drug Avonex, which is used to treat multiple sclerosis. (The name Biogen originally referred to “Biotechnology Geneva,” the city where the company was founded in 1978.) Biogen went public in 1983, and first set up a manufacturing plant in Cambridge in 1986. A Biogen drug approved in 2021, Aduhelm, targets Alzheimer’s disease.

(Danny Lewin, a co-founder of the company, was aboard a plane that left Boston on the morning of September 11th, 2001, and was killed trying to disrupt the hijacking.) Akamai today operates more than 300,000 servers around the world, and generates $3.5 billion in annual revenue—but when the founders were still at MIT, they were famously finalists in the school’s annual business competition, but not a winner.

In 2020, Moderna developed and received emergency use authorization for a COVID-19 vaccine based on its modified RNA technology. Moderna’s vaccine was among the fastest vaccines ever developed.

Later, it was home to the Walworth Manufacturing Company, where a Walworth employee invented an adjustable wrench with incredible gripping power called the Stillson that is still in use today. In 1876, when Walworth was based here, this building was the site of the first “long distance” demonstration of Alexander Graham Bell’s telephone, from a Walworth office in Boston to this building, with Thomas Watson manning the equipment on this end. The goal was to prove the usefulness of the telephone in business.

In the late 1930s, an inventor named Edwin Land moved in. On a vacation in New Mexico, Land’s daughter wondered why the photos taken in traditional film cameras couldn’t be seen right away—they had to be developed in a lab. That innocent question led Land to invent the first instant camera, and start a company called Polaroid to market it. Even though Polaroid’s headquarters moved elsewhere in Cambridge, Land kept his private research lab here. One entrepreneur who was inspired by Land was Steve Jobs, the co-founder of Apple Computer, who said that Land “saw the intersection of art and science and business, and built an organization to reflect that.”

Today, this brick building is occupied by LabCentral, a shared laboratory space used by dozens of fledgling biotech companies. When the building is open, you can go into the lobby and see small displays about the telephone and instant photography. If it's not open, see if you can find the accents above the building's windows that include fragments of railroad ties — a nod to the site's past.

There were also at one point 66 different candy companies in Cambridge, making everything from candy hearts for Valentine’s day to Squirrel Nut Zippers to lemon drops. (The Fig Newton cookie was also invented in Cambridge, in 1891—even though they were named for the nearby city of Newton.) This building is the last operating candy factory in Cambridge, owned by Tootsie Brands. The company unfortunately doesn’t offer tours, in part because candy companies are notoriously secretive about the equipment and processes they use to make candy—“Charlie and the Chocolate Factory” wasn’t too far off base. Inside, they make 26 million pieces of candy a day. Why is that number so high? The factory is the only place in the world that Sugar Babies and Junior Mints are made—both of which are small little morsels.

If you look through the parking lot on the right side of this building (or walk over to 250 Massachusetts Avenue), you can see the top of another candy factory. That one, the former New England Confectionery Company, or NECCO, has a water tower on top that now sports a DNA helix. When the building made NECCO wafers and conversation hearts (“Be Mine”)—from the 1920s until 2003— the water tower was painted like a rainbow roll of that chalky candy. At one time, it was the world’s biggest candy factory under one roof. The building is now occupied by the Novartis Institutes for Biomedical Research, the main research lab for the Swiss biopharma company. (Fun fact: like Willie Wonka’s factory, the building has glass elevators.) While Novartis and other biopharma companies design and test new drugs here in Cambridge, for the most part when they create something that is approved by the FDA and can be prescribed to patients, it’s made elsewhere. Cambridge’s real estate has become too valuable to do manufacturing these days—though the Cambridge Brands factory is hanging in there.

Across Main Street there is a mural that tells the story of candy manufacturing in Cambridge.

What next? There are other “off Trail” sites you can visit in Cambridge and beyond. (Scroll down to "Beyond the Trail.") If you’re hungry or thirsty, drop by Toscanini’s Ice Cream or Miracle of Science, two favorite hangouts of the Kendall Square and MIT communities a few steps away from the Cambridge Brands factory.