Domus Municipalis
Sé, Santa Maria e Meixedo, Portugal
The Domus Municipalis (municipal house) is a Romanesque building in the northeastern municipality of Bragança in Portugal. The exact function of this building, even after research completed in the 20th century, is still largely unknown: it could have served as cistern, but there are doubts if this was its primary function.
Palace data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).