Ridgewood Reservoir is a decommissioned 19th century reservoir and freshwater wetland on the border between the New York City boroughs of Brooklyn and Queens, within what is now Highland Park. Although the reservoir was originally built to secure a reliable water supply for the City of Brooklyn, it is positioned on the Queens side of the border in the neighborhood of Glendale. The reservoir and park are bounded on the north by the Jackie Robinson Parkway, on the south by Highland Boulevard, on the west by Vermont Place and on the east by Cypress Hills National Cemetery.

Brooklyn is a borough of New York City. Located on the westernmost end of Long Island, it is coextensive with Kings County in the U.S. state of New York. With 2,736,074 residents as of the 2020 United States census, Kings County is the most populous of the five boroughs of New York City and the most populous county in the State of New York. The population density of Brooklyn was 37,339.9 inhabitants per square mile (14,417.0/km2) in 2022, making it the second-most-densely-populated county in the United States, behind Manhattan, and it had the ninth-highest population of any county nationwide. Were Brooklyn still an independent city, it would be the fourth most populous in the U.S. after the rest of New York City, Los Angeles, and Chicago.