The city of Guanajuato in Mexico is filled with countless colonial era buildings standing along the narrow streets, small squares and adjacent to the old churches. There is a nice atmosphere thanks to street artists, dealers, and many tourists. However, the unique features of the city are underground tunnels. The first one was dug back in the colonial times. Originally, they were used for flood control, later carved into the rock tunnels were transformed into underground roads and streets.
