Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Tower of London' has mentioned 'Fortifications' in the following places:
Occurrence Sentence Text Source
[59] They were multi-purpose buildings, serving as fortifications (used as a base of operations in enemy territory), centres of administration, and residences.
William sent an advance party to prepare the city for his entrance, to celebrate his victory and found a castle; in the words of William's biographer, William of Poitiers, "certain fortifications were completed in the city against the restlessness of the huge and brutal populace.
The new fortifications were first tested in October 1191, when the Tower was besieged for the first time in its history.
[36] Even so, this was not sufficient to bring the castle up to the standard of contemporary military fortifications which were designed to withstand powerful artillery.