Palace of the Eleven Windows, Historic site and modern art museum in Cidade Velha, Brazil.

The Palace of the Eleven Windows is a two-story building with pale yellow walls and a dark hipped roof, its main facade pierced by eleven symmetrically placed windows and window-doors with straight lintels and railings, plus the main door. A simple entablature and corner pilasters divide the volume in the Portuguese plain style. The river-facing facade, reworked by architect Antônio José Landi, has arched openings forming loggias with railings on the upper floor.

Domingos da Costa Bacelar, owner of sugar mills at the mouth of the Guamá River, built the house in the 18th century as a weekend residence. In 1768 the Captaincy of Grão-Pará government bought it to house the Royal Military Hospital, which Italian architect Antônio José Landi adapted for the purpose. The hospital operated until the end of the 19th century; the building later held the Fifth Company of the Guard and, during the military dictatorship, Army Subsistence and political prisoners.

The building takes its name from the eleven symmetrical windows that structure its riverside facade and embody Portuguese architectural traditions. These openings define the place's visual character and are the first detail visitors notice when entering the courtyard.

The building stands in the Cidade Velha, the initial historic core of Belém, within the Feliz Lusitânia complex beside the Castle Fortress and the Cathedral. From its grounds there is a view of Guajará Bay and the Ver-o-Peso Market. The Sculpture Garden, the Corveta ship and a stage projecting over the bay are next to it.

The building's name comes from the eleven openings, windows and window-doors with straight lintels and railings, arranged symmetrically on the main facade alongside the main door. The river-facing facade, added by architect Antônio José Landi, has arched openings forming loggias with railings on the upper floor. A triangular pediment flanked by obelisks, added in the military period, was removed in the 2000 renovation.