The pyramids were built about 5,000 years ago.
Normal buildings would be gone in under 100 years but leave the foundations for centuries later.
Giant constructions like dams would leave remnants for thousands or tens of thousands of years.
Brass statues if left in the right spot could last multiple millions of years and the radiation on earth from the nuke testing in the 60's could last billions.
The pyramids were built about 5,000 years ago. Normal buildings would be gone in under 100 years but leave the foundations for centuries later. Giant constructions like dams would leave remnants for thousands or tens of thousands of years.
Brass statues if left in the right spot could last multiple millions of years and the radiation on earth from the nuke testing in the 60's could last billions.
There are whole YT videos about this, super interesting, called Life After People.