The Randstad (Dutch pronunciation: [ˈrɑntstɑt] ; "Rim City" or "Edge City") is a roughly crescent- or arc-shaped conurbation in the Netherlands, that includes almost half the country's population. With a central-western location, it connects and comprises the Netherlands' four biggest cities (Amsterdam, Rotterdam, The Hague, and Utrecht), their suburbs, and many towns in between, that all grew and merged into each other.
https://en.wikipedia.org/wiki/Randstad