Complex sentence: In 1835, a large dance and banquet hall was added to the house, and after the September 3rd 1843 Revolution, which forced King Otto to grant a constitution, the National Assembly convened here.
Split into simpler sentences: In 1835, a large dance and banquet hall was added to the house. After the September 3rd 1843 Revolution, which forced King Otto to grant a constitution, the National Assembly convened here.