How old has a site to be in order to qualify as a world heritage site?? Why do I ask??? Last year I visited the kazahk city of Turkistan in order to see the local whs (mausoleum of hodsha ahmed yassavi) there. One of the best whs I have ever seen in my life. I was deeply impressed.I stayed there one night but almost two full days. I had plenty of time to discover the gigantic caravan saray compley there,one of biggest projects in the history of kazahkstan.To tell the truth ...without any doubt ....the best shopping mall I have ever seen in my life......an excellent mixture of shops,disneyland and cultural heritage.....not as kitschy and pretentious like those in the Middle East like in Dubai, Abu Dhabi or Qatar and not as soulless as the countless american-style malls around the globe.
The Caravan Saray complex is truly unique in its kind, in its architectural appearance with its many local details and elements.
In my opinion it really has a lot of ouv......and who says that shopping malls can't be whs sites.
Only......the complex is relatively new. And so are other outstandingly newly built places.
Is there a time frame from the UNESCO regarding newly built facilities?

See https://www.worldheritagesite.org/forums/index.php?action=vthread&forum=6&topic=1595

Thank you,Els! I would never have found that thread by mself!

Brazilia, the capital of Brazil. 1960.

If we exclude memorial sites of recent conflicts from this analysis, the most recent single monument is probably:

Sydney Opera House, 1973

More of a quirk than an answer to this question, but El Hospital Divino Valles in Burgos is specifically inscribed as location 1029 of the Route of Santiago in Spain.

Hospitals would seem a fairly reasonable part of the pilgrimage route, but this is specifically the new building opened in 1985 on the by-pass outside the city. I had discounted it when searching, assuming it actually related to some medieval building in the centre, but no it is the pretty ugly one from 1985!

I'm quite sure they mean the location where the old hospital was rather than the new hospital. There are many sites where a new building is such as visitor centers etc

That was my assumption as well, but nope, it is specifically that hospital from 1985, outlining the footprint of the new building.
And across the road the police headquarters which looks like it is from the 1990's is also specifically included.

And this entirely nondescript bar and tabac seemingly built 20 years ago is included. In fairness it is exactly the sort of place I stopped for breakfast or a coffee when walking my little bit of the camino, but it seems surprising to give it WHS status.

Components 1029, 1127 and 1149 in these maps