The Old Croton Aqueduct

When New York outgrew its wells it built a covered brick aqueduct in 1842 to carry Croton River water forty-one miles by gravity into the city, a Roman idea in the American century. Much of it is now a state historic park you can walk end to end, straight over the buried tunnel, and the old brick weirs and the High Bridge over the Harlem River still stand. A real piece of hidden infrastructure, out in the open air.