Complex sentence: Coimbra is a municipality in central Portugal, whose core is the city of Coimbra, in the district of Coimbra, principal centre in the Centro region, seat of the Baixo Mondego subregion and former capital of Portugal during the Middle Ages.
Split into simpler sentences: Coimbra is a municipality in central Portugal, whose core is the city of Coimbra. It is in the district of Coimbra, being the principal centre in the Centro region, the seat of the Baixo Mondego subregion and former capital of Portugal during the Middle Ages.