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Photo: William England, Public domain via Wikimedia Commons
Go hiking or biking on the trailway that tops the original (now defunct) water supply to New York City. The trail runs on the western side of the county, passing through Yonkers, Hastings-on-Hudson, Dobbs Ferry, Irvington, Tarrytown, Sleepy Hollow, Briarcliff Manor, Ossining, and Croton-on-Hudson.
The Croton Aqueduct or Old Croton Aqueduct was a large and complex water distribution system constructed as part of the New York City water supply system between 1837 and 1842. The aqueducts, which were among the first in the United States, carried water by gravity 41 miles (66 km) from the Croton River in Westchester County to reservoirs in Manhattan. It was built because local water resources had become polluted and inadequate for the growing population of New York City. Although the aqueduct was largely superseded by the New Croton Aqueduct, which was built in 1885-1890, the Old Croton Aqueduct remained in service until 1955.