What treats should a building have to be used by people for next 1000 years?
I chopped my answer to three portions: Location, architecture and materials.
Location
To keep a building current and frequently used, it needs to be standing in a place where people are likely to still congregate centuries later. This might be impossible to predict exactly, but provided we don't have some serious innovations in transportation of both industrial products and people, waterways, railroad hubs and airports are places that will likely keep their relevancy as transit hubs. So building near or in industrial era built cities will be a good bet.
Of course the immediate centre of any city is the place where the most reconstruction and demolition happens, so the epicenter of a bustling metropolis might not be the greatest option. But if people are able to transit to your building effortlessly, it has the potential to still be used after a long time.
Architecture
It won't matter how close to a city centre the building lies if it's unusable but in a single purpose. Large, open amphitheaters can serve in a myriad of social events, which is why things like the Verona Arena are still in use: Location, architecture and these days the intrinsic value of a historical site.
The Spanish 100-year old church that was converted to a skate park serves as a good example of how even the most odd buildings can be reused with a little bit of effort. So as long as the building is designed in a way that it will be standing after a millenia, it can still be in use.
Materials
Pyramids and ancient ruins are mostly still standing because of the massive amounts of stone used to build them. They're not in their prior glory because of erosion, but the sheer volume protects them from being wiped out too quickly.
But I'm assuming you don't wish for tons and tons of granite slabs, but something more "modern", there's three possible solutions for materials: Concrete, metal and metamaterials.
Concrete
Concrete is already designed in some cases to last up to centuries of rough use. 87
High-volume intersections and highways in some cities in the US picked concrete for the more durable characteristics is has over asphalt. In buildings modern reinforced concrete has a few issues, namely the emphasis on rapid construction, more so than durability. This leads to corrosion in the reinforcements and cracking of the concrete in decades. But with proper design and material choices concrete could be a very potential candidate, especially if coated with..
Metals
With metals you get a lot of benefits over concrete. Things like far superior fracture toughness: Most metals bend and deform and are in general quite malleable in comparison to concrete and stone. Of course constant swaying will wear any metal down too and it will fracture just like concrete would.
Metamaterials
This brings us to the third category of potentials, which is the various metamaterials currently being developed. Self-healing plastics or even shape retaining, light reacting and self-healing polymers. Any sort of smart materials that would be usable or even mass producible are still probably decades away from reality, though.
All in all, the safest way to ensure your building is used after a millenia is to build it from huge stones and slightly off-centre of an active metropolitan area. 561