The Crusader structures called the Knights' Halls or the Citadel of Acre originally served as the Knights Hospitaller Compound. They extend over an area of c. 8,300 square meters. Archeological remains from the Hellenistic Period (300-63 BC), from the Early Arab Period (638-1099 CE), to a large extent from the Crusader Period (1291-1104 CE) and primarily from the 13th century, were uncovered in the compound area.
It was in the 13th century that Acre was the capital of the Crusader Kingdom of Jerusalem. The destruction of the Crusader structures during the Mamluk Period (1291-1517) left its mark on the compound.
During the Late Ottoman Period (1750-1918 CE), the citadel was built as part of the city's defensive formation on the ruins of the Crusader fortress and during the British Mandate (1918-1948), activists of Jewish Zionist resistance movements were held prisoner there and it served as the main prison in the North of Israel. The archaeological excavation of the Crusader remains and the exposure of a multi-period complex depict Acre's two golden ages – the thirteenth century and the eighteenth & nineteenth centuries.
References:House of the Blackheads (Melngalvju nams) is a building situated in the old town of Riga. The original building was erected during the first third of the 14th century for the Brotherhood of Blackheads, a guild for unmarried German merchants in Riga. Major works were done in the years 1580 and 1886, adding most of the ornaments.
The structure was bombed to a ruin by the Germans June 28, 1941 and the remains demolished by the Soviets in 1948. The current reconstruction was erected from 1995 to 1999. Today the House of Blackheads serves as a museum and sometimes concert hall.