This ancient and historic city houses many buildings going back to the early Middle Ages. Until it was overtaken by Amsterdam in the Dutch Golden age, Utrecht was the most important city in the Netherlands. It was and still is the See of the Archbishop of Utrecht, the country's most important Catholic leader. The University of Utrecht is the largest in the Netherlands. Before the city was fully canalized, parts of the Rhine River flowed through the city center. Most prominent of the historic buildings is the Gothic Cathedral of Saint Martin,  construction of which lasted  almost 200 years.