Classified as a national monument, nobody is quite sure what this unusual 12th century building was for! Built in a Romanesque style the building forms an irregular pentagon with a subterranean vaulted cistern https://www.travel-in-portugal.com/attractions/domus-municipalis.htm

The bone chapel is the most ghoulish sight of Portugal and thus one of the most memorable monuments of Evora. Inside the small chapel, the walls are lined with bones of the long-deceased, exhumed from the city's graves as the city expanded to allow further burials. http://www.evora-portugal.com/Guides/Evora-sights-attractions-sightseeing-things-to-see.html