A house just over five feet wide squeezed between two larger buildings on Calle Tetuán, painted pale yellow with two tiny balconies. The Narrow House began life as an alleyway and was eventually built over and inhabited; it is the narrowest house in the Americas and has its own street address.
It is not a museum — people live in it — but it is a popular photo stop. The street outside is otherwise unremarkable, but the curiosity of the building gives Old San Juan a certain reputation for the eccentric. Walk by, take the picture, move on.