Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Monuments of Oviedo and the Kingdom of the Asturias' has mentioned 'City walls' in the following places:
Occurrence Sentence Text Source
The following centuries (12thxe2x80x9316th) witness the development of the medieval city, the outlines of which are still preserved today, the construction of the city walls, a devastating fire which took place on Christmas Eve in 1521, and the aqueduct works, Los Pilares, constructed in order to provide the city with water throughout the 16th century.
One of the monastic settlements outside the city walls.