The Church of Saint Michael faces Holy Trinity Square in Tvrđa — its white twin-towered baroque facade is the most photographed view in Osijek. Built by the Jesuits between 1725 and 1748, the church was part of the Jesuit complex that included a college and gymnasium. The towers are identical and symmetrical, which is unusual for the Jesuit baroque style.
The interior is richly decorated with frescoes, gilded altars, and carved wooden choir stalls. The organ is original 18th-century work. The church is active and masses are held regularly; it is open to visitors between services. The Holy Trinity Column in the square outside the church, erected in 1729 to give thanks for the end of a plague epidemic, adds to the sense of a preserved 18th-century urban composition.