At the west end of Plaza de Mayo, the Cabildo Nacional (cabildonacional.cultura.gob.ar; free; 10:30am-6pm Wed-Sun) was the epicenter of the Revolución de Mayo in 1810, when Argentina declared independence from Spain. Covering events from from 1766 to 1823 the museum tells the history of Argentine colonial society, the English invasions of the Río de la Plata, the construction of Buenos Aires and independence. There are also details of the uses of the building, which was once the city's jail, and objects such as art works, medals, old clothes, and gold and silver shields are exhibited, together with explanatory posters.
Head up to the second floor for a great view of Plaza de Mayo from the balcony. In addition to the permanent exhibition, there are temporary exhibits and musical and recreational activities for the whole family.