Wetzlar is a small city in the state of Hesse, Germany. It is located in the Lahn-Dill-Kreis, about 100 km north of Frankfurt. Wetzlar has a population of about 62,000. The city is best known as the location of the headquarters of the optical manufacturer Leica Camera AG. The old city of Wetzlar has a well preserved market square surrounded by half-timbered houses. The city hall, built in 1529, is one of the oldest in Germany. There are also several churches, the most notable of which is the Stephansdom, a Gothic church which was built in the 13th century. The city is home to the University of Applied Sciences and Arts, Hesse.