The National Archaeological Museum, in the centre of Sofia, occupies the building of the largest and oldest former Ottoman mosque in the city, originally known as Koca Mahmut Paşa Camii. The construction started in 1451 under grand vizier Veli Mahmud Pasha but due to his death in 1474 the mosque has been completed in 1494. The museum was established as a separate entity in 1893 as the National Museum directed by Czech Václav Dobruský with its headquarters in the former mosque that previously housed the National Library between 1880 and 1893.
Prehistory Hall displays a collection of items dating from between 1,600,000 BC and 1,600 BC. The collection is chronologically displayed and includes various findings from caves around Bulgaria, tools of the earliest humans who inhabited its modern territory, drawings, simple pottery, ritual items and many others.
Treasury displays grave inventory and other treasures from the late Bronze Age to late Antiquity. Two of the most well-known Bulgarian treasures are located here: the Valchitran and Lukovit Treasures. Main Hall hosts a collection of diverse items ranging from ancient Thrace, Greece and Rome to the late Middle Ages.
The medieval Section includes a gallery of medieval books, woodwork, drawings, metal objects and other items characteristic of the era.
Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.