As the capital of Uruguay, Montevideo is home to a number of festivals and carnivals including a Gaucho festival when people ride through the streets on horseback in traditional gaucho gear. The major annual festival is the annual Montevideo Carnaval which is part of the national festival of Carnival Week, celebrated throughout Uruguay, with central activities in the capital, Montevideo. Officially, the public holiday lasts for two days on Carnival Monday and Shrove Tuesday preceding Ash Wednesday, but due to the prominence of the festival, most shops and businesses close for the entire week. During carnival there are many open-air stage performances and competitions and the streets and houses are vibrantly decorated. "Tablados" or popular scenes, both fixed and movable, are erected in the whole city. Notable displays include "Desfile de las Llamadas" ("Parade of the Calls"), which is a grand united parade held on the south part of downtown, where it used to be a common ritual back in the early 20th century. Due to the scale of the festival, preparation begins as early as December with an election of the "zonal beauty queens" to appear in the carnival.

What is the major annual festival in Montevideo?