Because it is a major tourist attraction and is constantly being maintained and repaired.
It's been around for around 45 years and it is still standing today.
The Eiffel Tower.
The Romans built the first fortifications on the sight (some of which can still be seen) but most of what is standing today was built by the Normans.
The Tower of London still has a small military garrison.
The Tower of London does not have any moats.The moat at the Tower of London is still there although it no longer has any water in it.
In The White Tower.
Yes. The Tower of London is one of London's most popular tourist attractions.
No. It's still standing.
Yes!
Yes
The Tower of London was, and still is, a fort and still has a small military garrison. It has also been a prison, a royal residence and a menagerie.
No.