Count Günther VII of Schwarzburg founded a Cistercian monastery in 1275 on the site of today’s Stadtilm Town Hall. The first abbess was Irmengard, a daughter of Günther VII.
Günther was in Jerusalem with Emperor Frederick II around 1228/29. He succeeded his father as Count of Schwarzburg-Blankenburg in 1236 and, after the death of his brother Henry III, became Count of Schwarzburg in 1259.
As a result of the Reformation, Stadtilm became Protestant in 1533, and the monastery was secularized in 1540. The property went to the Schwarzburg counts. The last abbess, Countess Margaret of Schwarzburg, left the city.
From 1628, the sons of Count Albrecht VII converted the building into Stadtilm Castle.
During the great fire of August 1, 1780, the castle built after 1628 (with the exception of the crypt and the tower) also fell victim to the flames.