Citadel of Târgu Mureș, Medieval fortress in Târgu Mureș, Romania.

The Citadel of Târgu Mureș is a pentagonal fortress of about 4.3 hectares with seven bastions linked by walls of river stone and brick. Five polygonal corner towers and the Gate Bastion survive, along with two square towers of the first enclosure. The Reformed Church and the History and Archaeology Museum stand inside.

In 1492 Stephen Báthory, voivode of Transylvania, built a fortress around an existing church and monastery to control the Székelys; it was destroyed in 1601 under Michael the Brave and Giorgio Basta. From 1602 the town's guilds rebuilt it as a pentagonal citadel with seven bastions of river stone and brick, finished around 1658. A moat surrounded it until 1910, and until 1962 its buildings served military purposes.

The guilds that built and manned the towers left their mark in stone: on the south facade of the Tailors' Bastion, a Latin inscription of 1638–1640 records that the guildsmen raised walls on empty ground and finished the tower under judge Szabó Péter and Tordai Pál Literatul. Two Gothic consoles built into the Shoemakers' Bastion were brought from the ruins of the monastery at Sîncraiu de Mureș.

The citadel stands in the city centre, with the Reformed Church in the southwest of the courtyard and the former commander's building in the southeast. The five corner towers and the Gate Bastion survive; their levels are linked by wooden stairs. A protective moat circled the walls until 1910, and the western side has a double wall.

The bastion preserves firing holes for cannons integrated into its walls, demonstrating medieval military engineering. These details are often overlooked but are clearly visible along the southern outer walls.