Google is no longer displaying any ads for searches for major tourist destinations, e.g. Venice, Santorini, Tenerife etc.
These are pages that include Google's travel guide knowledge graph, so a knowledge graph that includes no external citation source, and therefore no non-Google links.
In the past, there were so many ads displayed above the organic search results for these keywords, that there were often no organic results above the fold. I know from experience just how expensive these terms are to bid on, so Google have made a choice which does affect their bottom line.
[edited by: goodroi at 11:25 am (utc) on Apr 21, 2018]
[edit reason] TOS #24 [/edit]