The Islamic Center of Long Island (ICLI) is the oldest purpose-built mosque on Long Island. Its history dates to the 1970s, when a group of Muslim families, mostly recent immigrants to the area, started meeting on weekends to teach Islamic principles to their children. The group initially held meetings in private homes, a nursery school, and rented church facilities, and as the group grew, a permanent home was needed.
ICLI was formally incorporated in 1982, and purchased the plot of land on Brush Hollow Road in 1984. The plot had a small house, which was renovated to be functional for the community while the mosque was built on the adjoining lot. Ground was broken in December 1988, and construction was completed in 1991. The mosque was designed by Hirsch/Danois Architects, PC of New York, NY, who were inspired by visits to mosques in Shiraz and Isfahan. The original mosque building is approximately 7,000 sq. ft., constructed of split-faced concrete block, and includes prayer space, multipurpose space, classrooms, office space and day care facilities. An entrance iwan leads to a sky-lit atrium that divides the prayer hall from the multipurpose room, and when combined, the two rooms can accommodate about 500 worshipers. Classrooms and wudu (ablution) facilities are on the lower level. The mosque has a large green dome over the prayer hall, but no minaret.
In August 2013, the Center broke ground on a 19,000 sq. ft. addition, designed by the firm Urban Architectural Initiatives, founded by David Hirsch, one of the architects of the original mosque building. The addition will include more prayer space, new wudu areas, 12 classrooms, a day care room, administrative offices, a library, a community hall, space for seniors, and a cafe/lounge. The addition will wrap around a courtyard, with three pointed arches leading through the qibla wall to the court, and two new iwans at the west and north ends of the couryards.