Utrecht is the fourth-largest city of the Netherlands, as well as the capital and the most populous city of the province of Utrecht. The municipality of Utrecht is located in the eastern part of the Randstad conurbation, in the very centre of mainland Netherlands, and includes Haarzuilens, Vleuten and De Meern. It has a population of 361,699 as of December 2021. Utrecht's ancient city centre features many buildings and structures, several dating as far back as the High Middle Ages.