Linz has only been an independent Protestant parish since 1856. Until the beginning of the 19th century there had been no Protestant residents here at all. A prayer hall had been set up in the former Katharinenhof since 1845, and the moat gate served as the bell tower since 1857. When this was demolished in 1863, the city donated the hewn basalt stones to the community for the foundation of a new church. In 1864/65 the Trinity Church, a brick building with yellow facing bricks, was built in the arched style after Karl Friedrich Schinkel. At the corners of the three-axis nave, octagonal turrets were placed on square pillars, the flat-roofed brick hall has a recessed, arched semicircular apse. The square west tower - also with four turrets - has an octagonal bell chamber. The interior was redesigned after a fire in 1949. The three-winged altarpiece is the work of the Linz-born artist Edith Oellers and shows scenes from the New Testament.
The former Katharinenhof, an impressive, elongated half-timbered house, located next to the Protestant church, now serves as the community center. In the possession of the Cistercian Abbey of St. Katharinen since 1257, the sisters had the building rebuilt between 1695 and 1743. In 1845 the Protestant "Association for the establishment of its own parish" bought the Katharinenhof, which from then on served as a prayer room, pastor's and teacher's apartment. Since 1854 the newly founded Protestant elementary school has been teaching here The school was closed in 1939 and the children attended the Catholic elementary school until 1945. The school in Katharinenhof was reopened after the Second World War, and in 1961 it moved to the newly built school building in Bondorf and restored, today there is a youth café here, among other things.