As one of Puerto Rico's 78 municipalities, San Juan's government consists of two branches, the executive and the legislative. Those citizens eligible to vote directly elect the Mayor of San Juan and the municipal assembly for four-year terms. The municipal government is housed in City Hall or ''Casa Alcaldia'', which is located at 153 San Francisco Street, facing the Plaza de Armas at the center of Old San Juan. City Hall was constructed based on Madrid's City Hall starting in 1604 and finally completed in 1789.