Meta: What structures built today will be thought important/sacred/useful enough to be kept around for several hundred years?
In that vein, the Sagrada Família [1] might get finished this decade, was started in 1883, and is likely to be kept around for a couple centuries.
Possibly launch facilities at Cape Canaveral and Boca Chica.
With modern technology, we could probably take any building and through regular maintenance, keep it forever. On the other hand, we have weapons that can vaporize any man-made structure in an instant.
It is more about how significant it will be in the future, and we don't know. Maybe some random university building will be preserved for centuries because that's where the cure for cancer will be found. Maybe ITER, if it delivers on its promises, it will be of great historical significance, and maybe a bit radioactive. Maybe an airport or train station being built today that will become a major trade hub. An office building that miraculously survives a nuclear war. Some ugly structure that will be seen by generations as the most representative of 21th century art. Anything, really.
But with modern politics we do the exact opposite.
Ornamentation on the 50th floor is hard to see from the street, while a medieval city is mostly flat (2-5 stories) from afar.
Architecturally ornamentation is out and rarely tried now, so individual buildings don't stand out from the street perspective. Rather, the use of monumental forms (China TV building, London's Shard) are what set a building apart from the city now. And indeed the city itself has become a composition via skylines.
So although the buildings we construct now are much more austere than in the past, the city as a whole has acquired a third dimension which is where the originality plays out. So instead of individual structures standing out, entire cities now stand out.
On the subject of glass boxes, I can agree that they are forgettable.
[1] https://en.wikipedia.org/wiki/Millennium_Tower_(San_Francisc...
Some sites of historical significance were intentionally destroyed, particularly if the memory is painful. Most notably it has been very hard to preserve what remains of the Berlin Wall as a memorial.
There is, from the Berliners I've spoken too, a strong desire to make sure the memory of what the wall did isn't lost - but all but the most minute physical presences of the wall were actively removed.
A lot of these Cathedrals managed to survive long period of neglect with minimal to no maintenance.
There is a bit of survivor bias in there, but it's also a testament to the durability of these buildings.
If by "minimal maintenance" you mean frequent rebuilding after fires, refurnishing, extension of the building and stylistic changes, and almost continuous restoration effort, they you're right, of course.
Some of them being Great Wall of China, Taj Mahal, Machu Pichu, Petra, etc.
See:
> Thus, the Lindy effect proposes the longer a period something has survived to exist or be used in the present, the longer its remaining life expectancy. Longevity implies a resistance to change, obsolescence or competition and greater odds of continued existence into the future.[2] Where the Lindy effect applies, mortality rate decreases with time.