A visit to Copenhagen is incomplete without a trip to the ancient Danish capital of Roskilde , the seat of the country's ecclesiastical and royal power from the eleventh to the fifteenth centuries. There's been a community here since prehistoric times, and the Roskilde Fjord later provided a route to the open sea that was used by the Vikings. But it was the arrival of Bishop Absalon in the twelfth century that made the place the base of the Danish church - and, as a consequence, the national capital. Roskilde's importance waned after the Reformation, and it came to function mainly as a market for the neighbouring rural communities - much as it does today, as well as serving as dormitory territory for Copenhagen commuters. Nowadays, it's probably as well known for its summer rock festival as for its cathedral. There's enough to fill a day here, and quick transport connections to the centre of Copenhagen.