Assertion: mosque's roof | /r/HasProperty | flat
Facets:
Source sentences:
text: Most early hypostyle mosques had flat roofs on prayer halls, which required the use of numerous columns and supports.
text: Most early hypostyle mosques have flat roofs on top of prayer halls, necessitating the use of numerous columns and supports.
text: The first mosques had flat roofs on top of the prayer halls.