Tepito, also known as the "Barrio Bravo" or the "brave district", is a small working-class area in Mexico City in the historic centre, near Tlatelolco. It's known to be a "no man's land" where even the police would not go, and allegedly filled with crimes and you can buy anything there.
It is so named as people report robberies there often.
Their unofficial patron saint is the Santa Muerte, which is condemned by The Holy See and its supreme pontiff His Holiness The Pope Francis I, Sovereign of the Vatican City and Metropolitan Bishop of Rome. Its cult has spread across Latin America today. The altar itself, however, is not actually in the district of Tepito but next to it.