The aim of this paper is to reveal, describe, explain, and map variations in diurnal population in the metropolitan area of Prague. We use an alternative data source to traditional census-based cartographic presentations and employ location data from mobile phones to identify types of daily rhythm that shape the region at different times during a typical weekday. These rhythms are influenced especially by residential and commercial suburbanization and the consequent dynamic development of new working centres, services, and leisure-time facilities within the metropolitan region. The main output consists of three maps. The first map contains a typology of the main functions – residential, work, transportation, and services – and is used as the main analytical tool for sorting settlements, resulting in classification of nine types of settlement in all. The other two maps show a plastic image of the day- and night-time populations of the metropolitan area.