Originally the site of a Bethlehemite monastery, this plaza, the second-oldest square in the city, is where Argentines met to reconfirm their declaration of independence from Spain. On Sunday from 10am to 5pm, the city's best antiques fair takes over. You can buy leather, silver, handicrafts, and other products here along with antiques, all while tango dancers perform on the square. Sundays here are not to be missed and even locals come to enjoy themselves. The local restaurants also have outside seating here, but whether you're dining or watching the entertainment, keep a very close eye on your personal belongings.