The Inca ruled along the western coast of South America for a little over 100 years, until the Spanish invasion in the 16th century. The empire was centred around the city of Cusco, or Qosqo, in what is now southern Peru. This was the administrative, political and military center of the empire. In later years, it was also centred around Quito. The Inca were ruled by an Emperor known as the "Sapa Inca". Throughout their empire, they built many roads and bridges to make travel between their communities easy.