Complex sentence: It includes a museum in which it houses historical treasures, a library which keeps rare and valuable historical records, and the Grgurevo a site where the kings' castle from 1330 along with his remains are located.
Split into simpler sentences: It includes a museum in which it houses historical treasures, a library which keeps rare and valuable historical records. It also includes "Grgurevo", a site where the kings' castle from 1330 along with his remains are located.