Nationally, the most frequent style of architecture is Colonial, with slight variations as people adapt their homes to the climate of each region. Colonial-style homes are typical of the towns and cities settled by the Spanish Conquistadors, who replicated their construction style throughout the South American colonies. In Bolivia there are numerous beautiful Colonial homes in cities such as Sucre, Potosí and Cochabamba, where even today there are entire towns where the houses are of colonial architecture. Throughout the rest of the country, most major cities in Bolivia have what is called the "casco viejo" or "historical center", and some rural towns also preserve their Colonial constructions.