Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Castles and Town Walls of King Edward in Gwynedd' has mentioned 'Fortification' in the following places:
Occurrence Sentence Text Source
[29] A furious programme of building work commenced on the site under the direction of James of St George, the workforce sheltering in temporary huts in the centre of the half-built fortification.
[39] Edward, the Black Prince carried out extensive work at Caernarfon after he took over control of the fortification in 1343.