The Cathedral of Saint Mary Major, often called Lisbon Cathedral or simply the Sé, is a Roman Catholic cathedral located in Lisbon, Portugal. The oldest church in the city, it is the seat of the Patriarchate of Lisbon. Built in 1147, the cathedral has survived many earthquakes and has been modified, renovated and restored several times. It is currently a mix of different architectural styles. It has been classified as a National Monument since 1910.

Lisbon is the capital and largest city of Portugal, with an estimated population of 548,703 as of 2022 within its administrative limits and 2,871,133 within the metropolis. Lisbon is mainland Europe's westernmost capital city and the only one along the Atlantic coast, the others being on islands. The city lies in the western portion of the Iberian Peninsula, on the northern shore of the River Tagus. The western portion of its metro area, the Portuguese Riviera, hosts the westernmost point of Continental Europe, culminating at Cabo da Roca.