Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Defence Line of Amsterdam' has mentioned 'Fortifications' in the following places:
Occurrence Sentence Text Source
The UNESCO World Heritage Site known as the Defence Line of Amsterdam (in Dutch named Stelling van Amsterdam, pronounced [xcbx8cstxc9x9blxc9xaaxc5x8b vxc9x91n xc9x91mstxc9x99rxcbx88dxc9x91m]) is a 135-kilometre (84xc2xa0mi) ring of fortifications around Amsterdam.
The invention of the high-explosive shell and the percussion fuze, which allowed ordnance to explode on impact and dislodge brick fortifications easily, necessitated a change from masonry to concrete forts.
The Stelling van Amsterdam (Defence Line of Amsterdam) is a complete ring of fortifications extending more than 135 km around the city of Amsterdam.
The area around the fortifications is divided into polders, each at a different level and surrounded by dikes.
They mark the shift from the conspicuous brick/stone casemated forts of the Montalembert tradition, in favour of the steel and concrete structures that were to be brought to their highest level of sophistication in the Maginot and Atlantic Wall fortifications.
The fortifications have been preserved as they were designed and specified.