The consideration of the aspects that deserve special protection by the public administration
has been changing over time. Progressively it has change from an ancient and monumental idea to a much broader view. This change has arrived to the urban legislation in recent years.
The text presented reflects on this fact by analysing the academic work done for the
development of the "Catalogue of constructions in undeveloped land in the municipality of
Lleida". This document will be part of the review of the Urban Plan of the city. The paper
describes the study conducted for the proposed Catalogue. We will start by a presentation of
the general elements that set the planning regulations of Catalonia. Then we present the criteria
set for the buildings that should be preserved. Finally, we present the main features of the
approximately 150 buildings for which conservation is proposed as significant elements of a
space that preserves more than 800 years of human presence.