Ancient Indus Civilization "granary" excavations and materials. Note that the earlier interpretation of these constructions are Harappa and Mohenjo-daro in particular are not thought of as granaries by modern archaeologists; their purpose remains unclear.

Modern Harappa Granary

A good counter example to "Great Granary" having been used to store grain is this actual granary popular in the villages surrounding Harappa. Grain is stored in earthen structures, and accessed as needed through a re-sealable hole at the bottom.