The Mifflin School, built in 1825 is the oldest surviving school building used in the Philadelphia public school system. It is a two story, two bay red brick building, which now has its side walls stuccoed over. In the first phase of the development of the public school system in Philadelphia, 1818-1850, simple school buildings were built by local authorities in a decentralized system. During this period, 49 buildings were built by 7 local school boards, with only 4 surviving.