The Sant Pau Hospital of Barcelona at a first glance looks like a fairytale castle. Situated close to Sagrada Familia, this unique hospital was designed by the Catalan architect Lluís Domènech i Montaner. In 1997 it was declared World Heritage by UNESCO.
It was operating as a hospital till 2009 but because of it’s great cultural and historical significance now it offers its services to the public only as a museum. Unfortunately I didn’t know about it existence when I visited Barcelona.