Facing Largo do Senado is Macau’s most important historical building, the 18th-century ‘Loyal Senate’, which houses the Instituto para os Assuntos Cívicos e Municipais (IACM; Civic and Municipal Affairs Bureau). It is so-named because the body sitting here refused to recognise Spain’s sovereignty during the 60 years that it occupied Portugal. In 1654, a dozen years after Portuguese sovereignty was re-established, King João IV ordered a heraldic inscription that is displayed inside the Leal Senado's entrance hall.
Inside the entrance hall is the IACM Temporary Exhibition Gallery with rotating art exhibitions. On the 1st floor is the Senate Library, which has a collection of some 19,000 books, and wonderful carved wooden furnishings and panelled walls.