Assen is a city and municipality in the Northeastern Netherlands, and is the capital of the province of Drenthe. It received city rights in 1809. …Assen is a city and municipality in the Northeastern Netherlands, and is the capital of the province of Drenthe. It received city rights in 1809. Assen is known for TT Circuit Assen, the motorcycle racing circuit, where on the last Sunday in June the Dutch TT is run; and also for the annual Assen Dance Festival.