At the northern end of Central Park, hidden away from tourists and most locals, is a remnant of the War of 1812. Blockhouse #1 was built lookout tower to provide early warning should the British invade from the north. There were three other blockhouses along what is now Morningside Drive.
The building was assembled by volunteers who brought the building materials with them, hence the red sandstone blocks included with the Manhattan schist. Construction on the tower was completed in 1814, two days before the Treaty of Ghent was signed to end the war. Oh, well, at least we have an interesting relict to visit.
The blockhouse is normally locked. I happened to notice that the Urban Park Rangers were giving a tour last weekend so I took the opportunity to go inside. There's not a whole lot to see -four walls and a lawn- but the tour was free so I got my money's worth.