In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

A building material is?, Context: Few large stone buildings were constructed between the Constantinian basilicas of the 4th century and the 8th century, although many smaller ones were built during the 6th and 7th centuries. By the beginning of the 8th century, the Carolingian Empire revived the basilica form of architecture. One feature of the basilica is the use of a transept, or the "arms" of a cross-shaped building that are perpendicular to the long nave. Other new features of religious architecture include the crossing tower and a monumental entrance to the church, usually at the west end of the building.
stone