Roskilde is a city 30 km west of Copenhagen on the Danish island of Zealand. With a population of 52,974, the city is a business and educ…Roskilde is a city 30 km west of Copenhagen on the Danish island of Zealand. With a population of 52,974, the city is a business and educational centre for the region and the 10th largest city in Denmark. It is governed by the administrative council of Roskilde Municipality.