San Agustin Church in Intramuros is the oldest stone building in the Philippines, completed in its present form in 1607 and surviving intact through four centuries of earthquakes, fires, invasions, and finally the catastrophic Battle of Manila in 1945. Its thick baroque walls house the oldest Augustinian church in Asia.
The interior is extraordinary: a trompe l'oeil ceiling painted in 1875 to look like a barrel-vaulted nave from below, original wooden choir stalls inlaid with bone, and side chapels with period-appropriate paintings and sculpture. A small museum in the former monastery contains vestments, church silver, and historical artefacts related to the Augustinian mission in the Philippines. The church is a UNESCO World Heritage Site (as part of the Baroque Churches of the Philippines). Mass is still celebrated regularly.