UNESCO World Heritage city of Guanajuato, Mexico. Guanajuato is a beautiful mountain colonial town in central Mexico. The name of the city means “Place of Frogs” in the local indigenous language and therefore the frog is the city’s official pet. Many tourists and locals consider this city to be the most beautiful in Mexico. It used to be a major silver mining town, and many of the mines are still active. The city is built on very hilly ground, so virtually every point in the city is on a slant. The city has a network of underground tunnels that serve as roads making this place really unique in the world.