The south end of the park contains the Hills section of Governors Island, which covers 10 acres. The Hills consists of four hills that are high, and are made partially of reclaimed debris from the demolition of the island's former residential towers. From shortest to tallest, the hills are the 26-foot Grassy Hill; the Discovery Hill, with site-specific artwork; the 40-foot Slide Hill, which contains four long slides; and the 70-foot Outlook Hill, which contains an observation area with view of New York Harbor. The Hills includes over 41,000 shrubs and 860 new trees. The Hills cost $70 million to build; the construction of the Hills was funded in part by Google CEO Eric Schmidt, who donated $15 million.