Zagreb is the capital and the largest city of Croatia. It is located in the northwest of the country, along the Sava river, at the southern slopes of the Medvednica mountain. Zagreb lies at an elevation of approximately 122 m above sea level. The estimated population of the city in 2018 was 820,678. The population of the Zagreb urban agglomeration is 1,086,528, approximately a quarter of the total population of Croatia.