Complex sentence: But even during that short period he managed to do much: the town's development was being carried on; a theater, a college, a dancing school, a printing house, a newspaper, an orchestra, and a brick-yard were built.
Split into simpler sentences: But even during that short period he managed to do much. The town's development was being carried on: a theater, a college, a dancing school, a printing house, a newspaper, an orchestra, and a brick-yard were built.