Matthias of Arras (c.1290–1352), sometimes spelled as Matthew of Arras (Czech: Matyáš z Arrasu) was a French architect, famed for his work on St. Vitus Cathedral in Prague.Matthias was born in Arras, but little else is known about his early life. In 1344 he was summoned to Prague from the papal court of Avignon by Charles IV to lead works on the newly founded Saint Vitus Cathedral. He is also widely recognized as the architect of Karlstein Castle, although this fact is not fully authenticated.