One of the first things to do in Ushuaia is visit the Beagle Channel: take one of the many boats that go out to explore the wild fauna and marine life. You can take this trip throughout the year and it covers Bird Island, Isla de los Lobos, and continues until the emblem of the city: the Lighthouse Les Eclaireurs, a symbol of "doomsday" that in reality indicates to mariners their return to the Bay of Ushuaia.
The trips and various Ushuaia activities are awesome. Another trip goes out to the Bridges islands or "H" island, and are always led by an expert. Between November and March, the typical excursion is coupled with the "Penguin" excursion to Martillo Island, where a large colony of nesting Magellanic penguins resides. If you travel here during this time, this excursion should be on the top of your list of stuff to do in Ushuaia.
As for historical places to visit in Ushuaia, there's Civic Square of October 12, home to the obelisk that commemorates the place where the national flag was first flown in the Tierra del Fuego. The Provincial Legislature building, built in 1894 for the Governor's residence, currently houses the legislative branch of the government. Another one of the things to see in Ushuaia is the area's typical homes, normally carved with wooden ornaments, supposedly by prisoners.
Some more really interesting Ushuaia attractions include the train to the End of the World, a railway line in the Province of Tierra del Fuego. The station at the End of the World is located 8 kilometers west of the city and the train follows the path taken by the convicts in the early twentieth century to the Tierra del Fuego National Park. This park has an area of 63,000 hectares of Andes Patagonian Forest, and along with the dock of Eduardo Brisighelli, are two attractions in Ushuaia that you can't miss.
The city is full of charm and alternatives for tourists, don't miss any of the things to see in Ushuaia. To make sure you don't, plan your vacation by browsing through firsthand experiences shared by minube users about what to do in Ushuaia.