This museum is housed in the stunning beaux-arts Residencia Errázuriz Alvear mansion (1917), once the residence of Chilean aristocrat couple Matías Errázuriz and Josefina de Alvear. It now displays their art collection and other extravagant belongings, and is worth visiting for a glimpse into the world of Argentina's wealthy aristocratic families in the early 20th century, for whom these grand palaces with their elaborate marble staircases and ballrooms inspired by the Palace of Versailles were a status symbol.
Everything from renaissance religious paintings and porcelain dishes to Italian sculptures and period furniture was owned by Errázuriz and de Alvear, and some artwork by El Greco, Manet and Rodin can also be seen. Don't miss the wood-paneled Gothic-style central hall, created to complement the style of the religious tapestries it houses; concerts are sometimes held here. There are guided tours in English at 1:30pm Tuesday through Friday.