Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Historic Centre of Oporto, Luiz I Bridge and Monastery of Serra do Pilar ' has mentioned 'World Heritage' in the following places:
Occurrence Sentence Text Source
Located along the Douro River estuary in northern Portugal, Porto is one of the oldest European centres, and its core was proclaimed a World Heritage Site by UNESCO in 1996, as "Historic Centre of Porto, Luiz I Bridge and Monastery of Serra do Pilar".
The historic centre of Porto was declared a World Heritage Site by UNESCO in 1996.
The World Heritage Site is defined in two concentric zones; the "Protected area", and within it the "Classified area".
In 1996, UNESCO recognised Porto's historic centre as a World Heritage Site.
The Ribeira area along the river Douro, part of the UNESCO World Heritage Site
The "Historic Centre of Porto, Luiz I Bridge and Monastery of Serra do Pilar" is a Unesco World Heritage site.
The World Heritage Management Plan for the Historic Centre of Oporto includes a survey of the state of conservation, an action plan, a monitoring programme, and a communication plan.