Porkuni limestone museum tower was used as a sitting room of the school until 1991 when an exposition about the history of teaching deaf in Estonia was open. This was complemented by the limestone exposition which was initiated by the former county governor M. Pomerants. Once limestone was announced to be the national rock, the limestone museum was open in the fortress tower. This happened thanks to the help of Tallinn geologists. Today you can gain knowledge of how limestone was formed, different fossils and the use of limestone. You will find out more about the reasons why this unique museum in Europe is located just here. Good to know: -An A-b-c book for rock can be explored, describing all Estonian rock types There's a shop selling limestone items, possible to engrave on the item