Question: Extract the answer to the question from the following context. Question: Large solid pieces of hard material, such as rock with flat surfaces on each side are called? Context: W 122nd Street Seminary Row runs three blocks (1,500 feet (460 m)) west from the intersection of Amsterdam Avenue (Tenth Avenue) and terminates at the intersection of Riverside Drive. East of Amsterdam, Seminary Row bends south along Morningside Park and is resigned as Morningside Drive (Ninth Avenue). Seminary row runs in Morningside Heights, the district surrounding Columbia University, and crosses portions of Broadway and Claremont Avenue.
Answer:
blocks