The Old Croton Aqueduct Trail follows a historic aqueduct for 20+ miles from Yonkers to Croton Gorge Park (Croton Dam). It’s a popular spot for longer weekend walks. The mainly unpaved trail is a mix, winding through woods, towns, and historic sites. The path is not seamless — there are several on-road sections, and there are some parts where the way-marking isn’t great or there are missing signs. This site is a great resource, and here some free maps and an interactive map. The official southern trailhead starts in Yonkers just north of Van Cortlandt Park, and goes through Tibbets Brook Park.
The southern section, shown on maps as Old Croton Trailway State Park, is the most seamless, stretching from Yonkers Ave. just north of Tibbets Brook Park, goes for nearly 10 miles to Tarrytown, just shy of the Cuomo Bridge. It’s closer to the Hudson River.
The northern section, from Irvington to Croton Dam, starts east of Rt. 9, and passes through Sleepy Hollow Cemetery, Rockefeller State Park, Ossining, and near Croton Point State Park, ending at Croton Dam. This section is less seamless, with several on-road sections. A good longer stretch is the northern 2.5 mile section from Gerlach Park in Ossining to Croton Dam. See the hand-drawn map for help in navigating the connector sections.