St Trinitatis is the second great Protestant church of Wolfenbüttel, built between 1716 and 1719. From the outside it looks like a wide town gate — twin Baroque towers flank an arched passage through the centre — because that is exactly what it once was: the city gate of the old Heinrichstadt, converted to a church when the fortifications were dismantled.
The interior is high, pale, and luminous, with rococo galleries on three sides. The conversion from gate to church is one of the most unusual pieces of building reuse in Germany. Open during services and occasional afternoons.