How long can a structure or building survive, and what is the worlds oldest still standing today?
It actually depends entirely of what they are constructed from. If your hypothetical palace were built of stone and not affected by war and was in an area of little or no rain, then it might still be standing. However, the older civilisations (Sumerian, for example) often built using mud bricks (‘adobe’) which tend to crumble back to the constituent dirt. That is why many cities of the ancient Middle East are just ‘tells’ or heaps of dirt. Remember, the pyramids have deteriorated over the years – originally the largest pyramid at Giza, that of Khufu, was covered in gleaming white stone which has now totally disappeared. Now whether that is due to merely the passage of time, or whether the citizens of Cairo saw it as a convenient ‘quarry’ for building materials, I know not. Remember, buildings once left empty will often be used as a convenient source of stone, particularly if a period of relative unrest follows a period of civilisation – as happened with many of the Roman buildings of E
