The tramway
The Roosevelt Island Tramway, running from 59th Street and Second Avenue in Manhattan, is a cable car that crosses the East River in about 5 minutes, rising high enough to give a genuinely dramatic view of Manhattan, Queens, and the river below. It runs on the same OMNY/MetroCard fare system as the subway — no separate ticket needed — and is as much an attraction in its own right as a way to reach the island. The F train also reaches Roosevelt Island directly if you'd rather skip the tram on the way there and take it back (or vice versa).
Franklin D. Roosevelt Four Freedoms Park
At the island's southern tip, this park is one of the most striking pieces of modern civic architecture in New York — designed by Louis Kahn in the 1970s but not completed until 2012, decades after his death. A precise granite triangle narrows to an open-air "room" framing a view of the United Nations building and the harbor, built around Roosevelt's Four Freedoms speech. Free to enter, quiet, and genuinely moving as a piece of design.
The Smallpox Hospital ruins
Just north of Four Freedoms Park, the ruins of the Renwick Smallpox Hospital (built 1856, abandoned since the 1950s) stand as a deliberately preserved Gothic Revival ruin — lit at night, fenced but visible, and one of the more unusual sights in New York City precisely because so few visitors know it's there.
What else is on the island
Roosevelt Island is primarily residential — a planned community built in the 1970s — with a lighthouse at its northern tip, Southpoint Park, and Cornell Tech's campus (opened 2017) occupying much of the island's center. It's a quiet, low-key visit rather than a full day's itinerary: budget 2–3 hours including the tram.