This UNESCO World Heritage Site is a charming colonial-era city, Guanajuato is also the capital of Guanajuato state and nicknamed ” The place of Frogs” because the shape of the mountainous terrain. The heartland of Mexico they refer to is known as the Bajio. Silver was first discovered in Guanajuato a former silver minging city in the mid-1600s and home to the La Valenciana mine city Founded in 1559 . La Valencia was opened a century later and quickly became one of the richest and most productive silver mines in the world. The historic center of Guanajuato has a distinct European flavor with hundreds of narrow cobblestone callejones (alleyways) running up and down the hillside. Shady plazas are dotted with sidewalk cafés, museums, theaters, markets and historic monuments. The buildings throughout the city are fine examples of neoclassical- and baroque-style colonial architecture. An underground network of tunnels runs beneath the city helping to control the flow of traffic.