I’ve seen a couple of people doing this: go thorugh the list of UNESCO world heritage sites and note the ones you have been to. I count 83, so only 828 more to go… rather shamefully, there are two in Brussels (this and these) and one in Antwerp that I have not seen. It’s just as well that so many old capital cities are on the list or my tally would be considerably lower…
Austria
Azerbaijan
Belgium
Bosnia and Herzegovina
Croatia
Cyprus
Czech Republic
Estonia
Finland
France
Georgia
Germany
Greece
Holy See
Hungary
Ireland
Italy
Jerusalem
Kosovo
Luxembourg
Macedonia
Malta
Montenegro
Netherlands
Portugal
Russian Federation
San Marino
Spain
Switzerland
Turkey
Ukraine
United Kingdom
United States of America
Thanks – seems we have found a solution – will remember for next time though!