Bogotá is one of the great graffiti cities, and the reason is a specific and grim one: the police shooting of a sixteen-year-old tagger in 2011, the outcry that followed, and a city administration that responded by effectively decriminalising street art. What you walk through in La Candelaria is the result.
The tour is free and runs on tips, with fifteen dollars suggested. It goes on fixed daily departures from the Parque de los Periodistas; the guides carry blue umbrellas, which matters because imitators gather at the same square.
The private version is customisable and ends with a can of spray paint in your hand.