Assertion: keep's wall | /r/HasProperty | raised by a maximum of only 12 feet
Facets:
value: usually
type: TEMPORAL
Source sentences:
text: They were also relatively slow to erect, due to the limitations of the lime mortar used during the period – a keep's walls could usually be raised by a maximum of only 12 feet (3.6 metres) a year; the keep at Scarborough was not atypical in taking ten years to build.