The first religious building built by the 12th-century Christian crusaders in 1147, the cathedral has since survived many earthquakes and been modified, renovated and restored numerous times. 

The subsequent array of architectural styles and features reflects the cathedral’s evolution over the centuries. Its plain, fortress-like façade is punctuated with a great rose window above the main entrance; reconstructed from fragments of the original window after its destruction during the earthquake of 1755. Although the majority of the cathedral's architecture is Romanesque in style, there are considerable Gothic influences to be seen in sections added in the 13th-century. The most notable example of the latter is the cloisters, which were built on the foundations of a former Mosque - the remains of which can be seen thanks to partial excavations. 

On the second floor, the treasury collates a collection of suits, jewels and relics spanning various periods, most notably the casket containing the remains of St. Vincent, the official patron saint of Lisbon.