This neoclassical building is home to the two houses of the Argentine legislature - the senate and the chamber of deputies. Designed by architect Victor Meano, it took almost 50 years to complete. Work began in 1898, and, although the building was inaugurated in 1906, work continued for another 40 years, with Belgian sculptor Jules Dormal taking over the project after Meano was murdered by his butler.
The building is made largely from limestone, with a 80m-high bronze-plated dome - one of the largest in the city, and allegorical statues designed by Argentine sculptor Lola Mora.
Guided tours: The senate offers free guided tours on Mondays, Tuesdays, Thursdays and Fridays in English (12.30pm) and Spanish (5.00pm). Tours visit several rooms, including the chambers of both houses and the library. Enquire at the security window at Hipólito Yrigoyen 1849 - remember to take a photographic proof of identity.