The Carmo and Carmelitas churches stand almost touching on the same street near the University of Porto, separated only by a famously narrow house that was inserted between them to prevent the walls from meeting. The building is now one of Porto's most photographed curiosities.
The Carmo Church's exterior is the more dramatic of the pair: the south wall is entirely covered in azulejo tiles, painted in the 18th century with scenes from the life of the Carmelite order. The scale and detail of the tile work — visible from the street, slightly surreal in its setting — makes it one of Porto's landmark images. The Carmelitas church next door is more restrained, with a good Baroque interior. Both are worth entering.