Guild Wars 2

Basically, can you build one and stick it in your camp/keep and not have it despawn. Or does it have to be used every so often or face it despawning?

Nothing definitive has been said on that, but the premise, according to anet folks is if any siege isn’t ticked (used) every thirty minutes, it will despawn. However there have been reports of golems, in particular, despawning in fewer than 10 minutes if not ticked.