The preservation and protection of the cultural heritage sites is entrusted to the National Institute for Protection of Cultural Monuments. The Institute maintains the Central Register of Cultural Heritage. The Register currently lists 2,458 heritage sites classified in four categories: cultural monuments, archaeological sites, historic landmarks and spatial cultural-historical units. 200 of those are classified as being "of exceptional importance", and thus entitled to the highest level of protection. Further 582 are classified as being "of great importance", while the rest are "unclassified".