St. Nicolaikirche, Lutheran church in Oranienburg, Germany

St. Nicolaikirche is a neo-Romanesque brick church at Havelstraße 28, built from 1864 and consecrated in 1866. The yellow-brick pillar basilica is about 36.5 m long and 22 m wide, with a rounded apse and a 57.40 m west tower topped by a slate spire. Its main portal has a heavy wooden door with a copper leaf and a handle bearing the inscription "Frieden sei mit euch".

A first church was built in the 16th century and a makeshift church followed during the Thirty Years' War; both burned down. In 1658 a small Baroque church funded by Electress Luise Henriette was erected, destroyed in the town fire of 1788 and replaced in 1796 by a plain building that soon became dilapidated. On the urging of the congregation, King Friedrich Wilhelm IV commissioned Friedrich August Stüler to plan a new church, built from 1864 and consecrated in 1866. A fire at the end of the Second World War destroyed the building and its organ; reconstruction under architect Walter Krüger, supported by the Swedish Lutheran church of Uppsala, was consecrated on 26 October 1952.

The church is dedicated to Saint Nicholas and belongs to the Oberes Havelland church district, formed by merging the Oranienburg and Gransee/Templin districts; its parish also serves Schmachtenhagen and Germendorf. The square in front was named Pfarrer Ballhorn-Platz on 10 October 2016, honouring pastor Carl Friedrich Christian Ballhorn, who served the congregation from 1824 to 1870 and wrote the first extensive history of Oranienburg.

St. Nicolai stands at Havelstraße 28, close to Oranienburg's town centre; the square directly in front of the church has been called Pfarrer Ballhorn-Platz since 10 October 2016. The slender west tower rises 57.40 m and is easy to pick out when orienting yourself in the area.

The main portal's heavy wooden door has an ornate copper leaf and a handle inscribed lengthwise with the Bible verse "Frieden sei mit euch" (Peace be with you); a four-armed cross marks the handle's pivot point.