Part of the original penal colony, the Presidio building was built to hold political prisoners, murderous estancia owners, street orphans, and a variety of Buenos Aires' most violent criminals. Some even claim that singer Carlos Gardel landed in one of the cells for the petty crimes of his misspent youth. In its day it held 600 inmates in 380 cells. Today it's on the grounds of Ushuaia's naval base and holds the Museo Marítimo, which starts with exhibits on the canoe-making skills of the region's indigenous peoples, tracks the navigational history of Tierra del Fuego and Cape Horn and the Antarctic, and even has a display on other great jails of the world. You can enter cell blocks and read about the grisly crimes of the prisoners who lived in them and measure yourself against their eerie life-size plaster effigies. Of the five wings spreading out from the main guard house, one has been transformed into an art gallery and another has been kept untouched—and unheated. Bone chattering cold and bleak, bare walls powerfully evoke the desolation of a long sentence at the tip of the continent. Well-presented tours (in Spanish only) are conducted at 11:30 am, 4:30 pm, and 6:30 pm daily.