It is situated on the western side of the Republic of Bolivia. This region has been occupied by many cultures since 60.000 B.C. One of them was the first Andean empire, where the region's first planned city was erected: Tiwanacu. The city of La Paz, whose city planning was based on a group of square blocks, as all Spanish cities in America, still conserves these characteristics in the downtown area. Today, it is still the most important social, economic and political center of Bolivia and of the Andean region. La Paz has a highland climate with dry cold winters, with occasional snowfalls, and cool summers, due to precipitations.