St. Jakobi, Mühlhausen/Thüringen, Gothic church building in Mühlhausen, Germany

St. Jakobi is a Gothic church on Sankt Jakobi street in Mühlhausen's old town. It has a three-aisled nave vaulted in 1335, a stepped choir from the second half of the 13th century, and a twin-tower facade completed in 1418. Since 2004 a free-standing steel skeleton with concrete floors, holding the municipal library, stands inside the former church space.

St. Jakobi was first mentioned in 1296 as a filial church of St. Mary's. Excavations during the 1990s restoration revealed an 11th-century hall church on the site, extended with a west tower in the 12th century and surrounded by a cemetery, suggesting it was originally an independent parish. The stepped choir was built in the second half of the 13th century, the three-aisled nave from 1307 and vaulted in 1335; an inscription names 1386, and the twin towers were finished in 1418.

The church is named after Saint James and reflects the role it once played in the spiritual life of merchants and craftspeople who lived in this trading city. Today it serves as the municipal library, showing how sacred spaces adapt to serve their communities in new ways.

The church is located in the old town center near Lentzeplatz within the medieval fortifications and functions as a public library. Since it now serves as a cultural institution, visitors should check the library's opening hours to ensure access during their visit.

Thomas Müntzer was never pastor of St. Jakobi; the radical reformer preached in Mühlhausen, and the unrest of 1523–1525 centred on the Jakobikirche parish, home to many poor linen weavers. During the Reformation iconoclasm the church served as a store for furnishings removed from other Mühlhausen churches: precious vessels were locked in the tower, while wooden and stone saints were destroyed outside.