San Carlos Borromeo Church (Iglesia Parroquial de San Carlos Borromeo), also known as Mahatao Church, is in Mahatao, Batan Island, Batanes. The church's beauty and excellent state of preservation made it a National Cultural Treasure by the National Museum of the Philippines on July 31, 2001.
The church is made of stone and lime, common building materials in Batanes. An espadaña belfry is located on top of the facade's pediment with one of its bells dated 1874. The church has uneven wall thickness due to addition of step buttresses and even buttress walls. Its interiors, decorated in Baroque style, showcase floral designs sunburst ornaments painted in polychrome and gilt which lends a golden glow among the statuary.
On the right side of the facade is the church convent. The second floor of the convent is not the typical volada or cantilevered gallery for convents in the Philippines but an open extended deck. At the back of the convent are remains of an old circular well. Located on the left side of the facade is a beacon used for navigation.