I went to Park Avenue recently, and there were some really colorful sculptures on the medians...
Turns out that Niki de Saint Phalle's work is on display. From ArtLife Magazine: New York - Centered right in the heart of midtown on Park Avenue are
nine mosaic sculptures by the French Nouveau Realiste artist Niki de Saint Phalle. In collaboration with the city’s Parks Committee, the Niki Charitable Art Foundation (NCAF) has arranged with Nohra Haime, a major public installation of Saint Phalle’s sculptures on Park Avenue between 52nd and 60th on display from July 12th to November 15th.
Niki de Saint Phalle's Wiki.