 The southwestern corner of the reservoir was overlooked by Vista Rock, atop which Belvedere Castle was built in 1869.When Central Park was completed, the Lower Reservoir served as a complement to the Upper Reservoir, now the Jacqueline Kennedy Onassis Reservoir.As the Croton-Catskill Reservoir system was completed in the first decade of the 20th century, the Lower Reservoir came to be redundant.