Assertion: roman concrete | /r/HasProperty | developed
Facets:
value: a century before that
type: TEMPORAL
Source sentences:
text: It is uncertain when Roman concrete was developed, but it was clearly in widespread and customary use from about 150 BC; some scholars believe it was developed a century before that.
text: It is uncertain when Roman concrete was developed, but it was clearly in widespread and customary use from about 150 BC; some scholars believe it was developed a century before that.