Avenida 16 de Julio — universally called El Prado — is the spine of central La Paz, running downhill for over a kilometre with a broad tree-lined median between two lanes of traffic. It connects the upper commercial districts to the lower city and serves, in the way that good urban boulevards do, as the place where the city watches itself. Shoe-shiners in balaclavas work one end; street vendors selling phone accessories, pirated DVDs, and salteñas from baskets occupy the middle; and the cafe terraces of the larger hotels face out onto the pedestrian median from both sides.
The monuments along the median are worth pausing at — they tell a compressed version of Bolivian political history, with Simón Bolívar and various independence-era figures appearing at intervals. The pedestrian stretch near Plaza del Estudiante at the upper end is the most animated, particularly in the late afternoon when office workers and students fill it. El Prado is not especially beautiful by the standard of great South American boulevards, but it's real: an honest cross-section of who La Paz is, played out on a single street. Walk it end to end once.