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, making it the sixth highest capital in the world by altitude. 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. Asmera was first settled in 800 BC with a population ranging from 100 to 1000. The city was then founded in the 12th century AD after four separate villages unified to live together peacefully after long periods of conflict.