Complex sentence: In 1718, he founded in 1718, a small free school where twelve poor boys were housed, clothed, fed and educated by just one teacher, in a building not far from the present Cathedral of St. Thomas in Fort, Mumbai.
Split into simpler sentences: In 1718, he founded a small school where twelve poor boys were given free housing, clothing, food and education. The school, which had just one teacher, was located in a building not far from the present-day Cathedral of St. Thomas in Fort, Mumbai.