The entire city area of Lübeck was added to the UNESCO World Heritage list in 1987.
Notes on verification
UNESCO inscription in 1987 is confirmed by official UNESCO and city sources, and it was indeed the first time an entire historic old town/quarter (rather than a single monument) was listed in Northern Europe. However, the claim's phrasing 'entire city area' overstates the case: the inscription covers roughly 75% of the historic Altstadt (excluding areas destroyed in WWII and rebuilt), not the whole modern city or even the full old town.
Sources
- Zauberer der Worte – Thomas Mann (blog.dnb.de)
- https://whc.unesco.org/en/list/272 (whc.unesco.org)
- https://whc.unesco.org/document/153083 (whc.unesco.org)
- https://www.luebeck.de/de/rathaus/verwaltung/stadtplanung/altstadt/unesco-welterbe-luebecker-altstadt/index.html (luebeck.de)
- https://www.sh-tourismus.de/en/culture/unesco-world-heritage (sh-tourismus.de)