Konstantin Totev's team of archaeologists dug up the foundations of a building under Trapesitsa Hill considered to be "the first Asen dynasty castle - that of Asen, Teodor and Kaloyan" in Bozhidar Dimitrov's (director of the National History Museum in Bulgaria) words.The building is situated in the northern part of the temple on steep rocks which guarded the Arbanassi road in the past. Its walls seem to have been extremely wide - 4, 5 m., having in mind that the usual Mediaeval walls width was 2, 2 m.According to Dimitrov, the castle is very well preserved and there are living areas, storages, shops, a church and a barrack in it.Restoration is necessary, however, as some of the stones from the structure look unstable.