Mies Van Der Ro·he (mēz' vān dər rō'ə, rō', fän, mēs') German-born American architect considered a founder of the International Style. His steel-frame and glass buildings include the Seagram Building in New York City (1956-1959) and the Chicago Federal Center (1963-1968). Mies'i·an (mē'sē-ən) adj.