Complex sentence: Saint Columban College has three (3) campuses although the Grade School and High School campuses are on physically interconnected lands, they are technically separated by the boundary between Balangasan and Sto.
Split into simpler sentences: Saint Columban College has three (3) campuses. Although the Grade School and High School campuses are on physically interconnected lands, they are technically divided by the boundary between Balangasan and Sto.