The Washington Monument is made of marble, granite, and soapstone.
 The marble pyramidion has thin walls only 7 inches (18 cm) thick supported by six arches, two between opposite walls that cross at the center of the pyramidion and four smaller corner arches
 The total number of blocks in the monument, including all marble, granite and gneiss blocks, whether externally or internally visible or hidden from view within the walls or old foundation is over 36,000

