The school building of the then Reform Realgymnasium was built in 1927.

The secondary school An der Burg 19 was given the name "Erweiterte Oberschule" in 1959 and from 1975 to 1990 it was called "Erweiterte Oberschule Erich Weinert".

Since August 1, 1991, the building has been home to the state Tilesius Gymnasium, named after the Mühlhausen natural scientist Wilhelm Gottlieb Tilesius von Tilenau.