As I was thinking about how fun it would be to have a job where you solve puzzles in the world, it struct me that media never depicts archeology in a real light. My short search seemed to confirm my thoughts. Most ancient sites are not guarded by elaborate traps or secret riddles to get in. From what I’ve found there were some crossbows here and there. Some rare hidden rooms with a lot treasure, but again, no traps.
A large stone on a ramp, kept from rolling by a wedge, to be pushed out of position, by use of mechanical advantage through a lever, seems quite doable to me. You could even utilize a smaller initial stone to kick the wedge withholding a larger stone.