The island is accessible by numerous modes of transport, including a bridge, an aerial tram, and the city's subway and ferry systems.

[14] The island is one of the southernmost locations in New York City where Fordham gneiss, a type of bedrock commonly found beneath the South Bronx,[15] can be seen above ground.

[7] The layer of bedrock is shallow and is covered by glacial till, and a 2012 study found no evidence of ponds or streams on the island.

[19] Roosevelt Island's street layout is based on a master plan designed in 1969 by the architects Philip Johnson and John Burgee.

[26][8] Archeological studies have found shell middens just opposite the island, along both the Queens and Manhattan shores, and the Lenape are known to have had settlements around waterways.

[60][73] The United States Department of the Navy proposed a drill ground and training facility at Blackwell's Island's northern end in 1901,[74] although city officials opposed it.

[97] The city's deputy correction correctioner called the island's penitentiary "unfit for pigs" in a 1914 report criticizing the unsanitary and overcrowded conditions,[98] and a grand jury investigation the same year found that the jail was severely mismanaged.

[179] The New York state government proposed in December 1967 to convert most of the island into a public park, except for senior citizens' housing at the north end.

[182] Other plans included a mix of recreational facilities and low-density housing;[183] an amusement park similar to Tivoli Gardens in Copenhagen;[183][184] an underground nuclear power plant;[185][173] a cemetery;[186] and a "city of the future".

[187] In February 1968, mayor John V. Lindsay named a committee to make recommendations for the island's development,[173][188] at which point one newspaper called it "the most expensive wasteland in the world".

[192] Land clearing began that April,[184][193] and Lindsay asked the New York State Urban Development Corporation (UDC) to help redevelop the island in May.

[186] The architects Philip Johnson and John Burgee designed the master plan for Welfare Island, which called for two neighborhoods named Northtown and Southtown, separated by a common area.

[214] The WIDC approved a proposal for 1,100 middle-income and luxury apartments in April 1972;[221] the UDC decided to build the residences as housing cooperatives after unsuccessfully looking for a private developer.

[215] The United States Department of Housing and Urban Development formally designated Welfare Island as a "new town" in December 1972, making it eligible for additional funds.

[229] UDC head Edward J. Logue and project manager Robert Litke convinced multiple developers to sign 40-year leases for buildings on the island.

[254] New York state comptroller Edward V. Regan published a report in 1980, saying that the Roosevelt Island redevelopment suffered from severe cost overruns and was losing money.

[272] The New York City Board of Estimate approved plans for Southtown in August 1990,[273] but the project had been placed on hold by 1991 because RIOC had not been able to secure a developer.

[276] To attract visitors, RIOC developed several recreational facilities and parks and sought to restore the island's oldest buildings.

[318] RIOC began soliciting plans for a memorial to the journalist Nellie Bly in 2019;[319] it ultimately commissioned The Girl Puzzle monument by Amanda Matthews,[320] which was dedicated in December 2021.

[324] When the first residential buildings opened, Roosevelt Island's amenities and wheelchair accessibility made it attractive to disabled residents and families with children.

[343] There have been community traditions on Roosevelt Island, such as Halloween parades, Black History Month events, and Lunar New Year celebrations.

[297][5] In addition to the apartment buildings, the northern part of Roosevelt Island contains the Metropolitan Hospital's former church, which was built in the 1920s and became a wedding venue in 2021.

[366] Roosevelt Island has six buildings and structures that are New York City designated landmarks,[312][367] all of which are also on the National Register of Historic Places (NRHP).

[371][372] The ruins of the City Hospital, a mid-19th-century building on the southern tip of the island, had been listed on the NRHP,[373] but were razed in 1994 due to extreme neglect.

[404] In 2019, mayor Bill de Blasio's office told reporters that the firehouse would not reopen because the island already had additional emergency services.

[408] Near the south end of the island is Southpoint Park, a seven-acre (2.8 ha) green space containing the Strecker Lab and Smallpox Hospital buildings.

[303][411] Four Freedoms Park was designed by Louis Kahn in 1974[412] and consists of two rows of trees converging toward a granite "room" at the island's southern tip.

[430][431] Two residents, Dorothy and Herman Reade, founded the island's first library within a rented space in 1976; the collection had moved to 625 Main Street by 1977.

[443] Until its development in the late 20th century, Roosevelt Island was largely inaccessible from the outside world, and a guard banned most visitors, including all children under age 12.

[445] Although the tramway and subway stations are both wheelchair-accessible, both modes of transit can experience outages that occasionally make it impossible for disabled residents to travel to and from the island.