Complex sentence: Such was the press on the new high school, which originally stood as two separate buildings for boys and girls, that the City was compelled to open Overbrook High School in 1926; a third high school, John Bartram, followed in 1935.
Split into simpler sentences: Such was the press on the new high school, which originally stood as two separate buildings for boys and girls, that the City was compelled to open Overbrook High School in 1926. A third high school, John Bartram, followed in 1935.