Ex Casa de Gobierno, National historical monument in Ushuaia, Argentina

The Ex Casa de Gobierno is a single-story white wooden building in Ushuaia with a centered balcony above the main entrance. Its interior contains eleven rooms connected by two corridors, two hallways, and two vestibules, all featuring stamped sheet metal ceilings and metal wall panels.

The building's construction date is uncertain: documents and plans were lost in a 1920 fire at the previous government seat, and estimates range from 1886 to 1893. The project came from the Dirección General de Obras Arquitectónicas under architect Francisco Tamburini, dated 17 September 1885; Governor Félix Mariano Paz sailed from Buenos Aires with the disassembled house on 14 January 1886. It was later enlarged with an upper floor and served as governors' residence, then government house, and briefly as police headquarters from 1976 to 1983.

The building's name, Ex Casa de Gobierno, recalls its role as the first seat of the government of the National Territory of Tierra del Fuego, Antarctica and the South Atlantic Islands. From 1983 to 1991 it housed the first Territorial Legislature, and its sessions included the Constituent Convention that sanctioned the provincial constitution on 17 May 1991.

The building is an annex of the Museo del Fin del Mundo, whose main site lies 300 metres to the east, so the two can be visited on one walk through central Ushuaia. It has served official purposes for over a century and is a National Historic Monument, so only the exterior is normally seen by passers-by.

The building was shipped from Buenos Aires disassembled: Governor Félix Mariano Paz boarded with the packed house on 14 January 1886. The plans were signed on 17 September 1885 by the Dirección General de Obras Arquitectónicas under architect Francisco Tamburini. Because a 1920 fire destroyed the construction papers, the exact build date remains unknown, estimated between 1886 and 1893.