Solve the Ancient Riddle

In the land of the Pharaohs, where the pyramids touch the sky, I am the answer to the question that has puzzled the wisest of the wise.

I am not a creature, nor a thing, nor a place, nor a time. I am the solution to the riddle that has been hidden in plain sight, for all to see, yet none have seen.

What am I?

For those who are worthy, a hint is hidden here...

But be warned, the answer is not for the faint of heart, nor the dim of mind. You will need speed and thought to unlock it.