By Anne Levin

One of the most breathtaking views of Manhattan can be had during a four-minute ride across the East River. In a red capsule suspended 250 feet above the water, a conveyance known as the tram transports passengers from the noise and congestion of the Upper East Side to Roosevelt Island, a surprisingly peaceful expanse less than a mile away.

The view gets even more impressive once passengers arrive on the island. But this sliver of land lying between Queens and Manhattan has a lot more to offer than a breathtaking vantage point for ogling the city’s skyline.

Roosevelt Island is home to some 14,000 people—a number bound to multiply as Cornell University expands its technology campus there over the next two decades. For now, the island remains a kind of oasis—treasured by residents for its small-town flavor; favored by visitors for its green space within gawking distance of the city.

“The best thing about living here is that it’s so quiet,” says Barbara Lippert, an advertising columnist and commentator who moved to the island in 2013. “You leave the din of Manhattan behind, especially when you’re taking the tram. You just glide here and you get off and it’s green, narrow, and surrounded by water. And with the million dollar view, you almost want to cue the Gershwin music, especially at night. It’s very romantic.”

Known throughout its history as Hog Island, Manning’s Island, Blackwell’s Island and Welfare Island, the expanse was renamed to honor Franklin Delano Roosevelt in 1971. The FDR Four Freedoms Park at the southern tip, designed by late architect Louis Kahn, is a major tourist attraction and a favored spot for locals who find solitude on its gently sloping lawn bordered by Linden trees. In spring, the walkways along the river are lined with lush cherry blossom trees in full, pink bloom.

Another architectural curiosity, The Octagon, sits near the northern end. Alexander Jackson Davis designed this five-story, blue-grey stone rotunda for the New York City Lunatic Asylum in 1841. Many decades of decay and two fires later, the building was added to the National Register of Historic Places in 1972 and has since been renovated as the central lobby of a 500-unit apartment complex. The lobby is open to visitors and is lined with historic photographs.

Sitting between these two architectural anchors are parks, playing fields, a theater, a few restaurants and stores, and several high-rise residential buildings. Some 80 percent of the residents commute to Manhattan via the tram or the F subway train, which added a stop in 1989. While many of the island’s children are educated in Manhattan, others remain on the island to attend the public school, which goes through eighth grade.

There were only 5,000 people and four apartment buildings when Judith Berdy migrated to the island from Manhattan 38 years ago. She is the author of Roosevelt Island: Images of America and president of the local historical society. “It’s a communal community—a small town with lots of activities,” she says. “I moved here because it was affordable, it was new, the tram was running, and it was safe. It was completely different from Manhattan, where I’d be in a fifth-floor walkup looking at a brick wall.”

The city of New York purchased the island from the prosperous Blackwell family, who lived across the river in Queens, around 1825. One of the first institutions to be built was Blackwell’s Island Penitentiary, which kept expanding beyond its massive stone walls.

According to an article by Ms. Berdy in Politico, the prison drew a number of public intellectuals over the years. “One was influential essayist and political anarchist Emma Goldman, who was imprisoned there for a public demonstration at an unemployment rally in New York’s Union Square,” she wrote. “Found guilty of fomenting an unlawful assembly, Goldman was sentenced to a year in Blackwell in 1894 — the same year that Goldman’s friend and idol Eugene Debs led the famous Pullman Railroad strike, which Goldman would have doubtless supported had she been able.”

Conditions at the prison and other Dickensian structures including the lunatic asylum, a charity hospital, a smallpox hospital, and a workhouse, were notoriously grim. In 1921, the name was changed to Welfare Island as a series of reforms were put into place. The prison was moved to Rikers Island in 1935, new hospitals were created, and a residential community began to take shape.

Today, there are several apartment buildings on the island, many of which are home to young families of researchers at Cornell and Sloane Kettering Memorial Hospital across the river. The visitor’s center, located in an old kiosk near the tram stop, offers walking tours and other activities. “We can direct you down to the FDR park and to the six landmark buildings, the lighthouse, the art gallery, and other attractions,” says Ms. Berdy. “But most people just come from Manhattan to walk on the promenade.”

The skinny stretch of mid-river land is no longer New York’s best kept secret. Just how it will accommodate the new residents and workers at the Cornell Tech Campus over the next 20 years, the master plan designed by Skidmore, Owings & Merrill, remains to be seen. The first phase will include an academic building, co-working space for start-ups, housing, and facilities.

“My biggest fear is that it’s going to get overcrowded and congested,” says Ms. Lippert, who lives in a high rise close to the tram and subway stops. “I’m not sure they have planned for the transportation problem. The subway doesn’t often run on weekends because they’re still fixing it from Hurricane Sandy. And on weekday mornings, it’s so packed that it’s already a mess.”

In June 2015, Hillary Clinton chose Roosevelt Island’s Four Freedom’s Park, which was named in honor of the four freedoms FDR articulated in his 1941 State of the Union address, to make the first policy speech of her own presidential campaign. That event put the island into the international spotlight and drew thousands of spectators and supporters.

But so far, it still offers a welcome measure of peace. “If I’m out walking at night on the promenade, I’m among very few people,” says Ms. Lippert, who regularly shares beautiful photos of the Manhattan skyline on Facebook. “There is really no place like it.”