Olvera castle was built in the late 12th century as part of the defensive system of the Emirate of Granada. The castle was seized from the original Moorish builders and occupants and redesigned and expanded under King Alfonso XI in 1327.
Situated at the highest point of the town, the castle has an irregularly-shaped elongated triangle that fits the form of the rock base.
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.