Constructed as a fortified stone church by Jesuit missionaries in the 17th to 18th centuries and completed in 1792 atop a strategic hill overlooking the Boac River, the Immaculate Conception Parish Church (Boac Cathedral) is a prime example of Spanish-era Hispanic Gothic fortress architecture. Its massive meter-thick terracotta stone buttresses and towering belfry originally served as a sanctuary and defensive redoubt protecting townspeople from Moro pirate raids. The cathedral's interior features beautifully restored wooden retablos and original ceiling frescoes. It is dedicated to Our Lady of Prompt Succor (Ina ng Biglang Awa), the patroness of Marinduque, who according to island lore miraculously appeared on the fortress wall in the 18th century to drive away invading pirates. **Traveler Logistics:** Located in the heart of Poblacion Boac. Visitors can walk up the historic cobblestone steps from the town plaza. Modest dress is required inside the sanctuary.