Tracking category for {{Listing}}, with |wikipedia= but not |wikidata=. This category is not added if the Wikipedia link is to one section of a larger article (i.e. field contains # character).
This website uses the Wikivoyage API to get and display all the information you see. This is the MediaWiki API, which is a general API for accessing data from Wikimedia projects. You can find information about it here: MediaWiki API.