Asmara ( əs-MAHR-ə), or Asmera, is the capital and most populous city of Eritrea, in the country's Central Region. It sits at an elevation of 2,325 metres (7,628 ft), making it the sixth highest capital in the world by altitude and the second highest capital in Africa. The city is located at the tip of an escarpment that is both the northwestern edge of the Eritrean Highlands and the Great Rift Valley in neighbouring Ethiopia. In 2017, the city was declared as a UNESCO World Heritage Site for its well-preserved modernist architecture. According to local traditions, the city was founded after four separate villages unified to live together peacefully after long periods of conflict. Asmara existed as a major settlement for over half a millennium and enjoyed some importance as it stood on the trade route to Massawa. Asmara first rose to prominence during the 20th century, when it became capital of Italian Eritrea. Under Italian rule the city of Asmara experienced rapid urbanization and modernization.