A late creation by area standards, Bergisch Gladbach was founded in 1856 as a city district comprising several smaller (and older) towns, with a total population of about 105,000. The 10th-century St. Johann Baptist Church at Refrath is Bergisch Gladbach's oldest building. The Bensberg Rathaus (or town hall, nicknamed "Affenfelsen," or Monkey Rock) is a nationally known tourist attraction. Schloss Bensberg and Schloss Lerbach, both former castles, are now among Germany's top luxury hotels.