Sé patriacal is Lisbon's cathedral. Since it is the oldest church in Lisbon, it suffered many accidents like the earthquake in 1755 and had to be modified each time. It was built on a site of an ancient mosque built in 1147. Today, its architecture appears today as a blend of different styles, all contemporaneous at the time of the construction and modifications. The two towers and the rosace remind the Roman style. The chapels and the cloister are gothic. The building is very imposing and austere. Though the entrance to the cloister is not free, it is worth it if you want to admire the Sao Vicente's relic (Saint Vincent, patron of Lisbon, IVth century). His remains were brought from the Cabo Sao Vicente to the capital city in 1173.
To see: the façade, the cloister, the relic.