Modrý Kameň is the smallest city of Slovakia. The city was founded under the medieval castle of 12 century and it was the administrative center of Novohrad. In the 20th century, however, that position was overtaken by Veľký Krtíš. These cities are known for mining brown coal, although this is declining. Gothic castle is a castle ruin now and in the nearby mansion visiters can view the Museum of Puppet Cultures and Toys.