Ghent is a port city in northwestern Belgium, at the confluence of the Lys and Scheldt rivers. During the Middle Ages it was a prominent city-state. Currently, it is a university city and a cultural center. Its pedestrianized center is famous for its medieval monuments, such as the 12th-century Castle of the Counts of Flanders and Graslei Street, a row of guild houses along the Lys River harbour.