The original San Agustin Church was the first religious structure constructed on Luzon Island and was completed in 1571. The present church was fiinshed in 1604 and is the oldest church still standing in the Philippines; no other surviving building in the Philippines has been claimed to pre-date San Agustin Church.

Intramuros is the oldest district and historic core of Manila. Nicknamed the 'Walled City'; the fortified Intramuros was the full extent of the City of Manila and the seat of government during the Spanish Colonial Period. Its name in Latin; intramuros; literally means 'within the walls'. Districts beyond the walls of Manila were referred to as extramuros; literally 'outside the walls.'

The city was located then along Manila Bay and south of the Pasig River entrance; before 20th-century reclamations obscured the city from the bay. Guarding the city is Fort Santiago; a citadel located at the mouth of the river. Construction of its thick defensive walls were started by the Spaniards in the late 16th century to protect the seat of the Spanish government from foreign invasions (most notably British and Dutch) and raiding Chinese sea pirates.