Sam may be right about modern vaults. However, I have a vault here at the store, and had one in a previous store. Both are steel with concrete filling.
I asked my safe guy and he says they are just plain steel with concrete. He had no idea what type steel.
I have watched the alarm folks drill into several safes and the two vaults and it seems to drill like mild steel. Certainly nothing extra hard.
I have a friend who manages the old Bank of America main office building in downtown Norfolk. It is apartments now and called The Icon.
All three sub-basement floors are the vault rooms. There are about 8 various size vaults on the one floor which was mostly financial securities offices.
The next floor was the counting rooms, and there are three big vaults, each sub-divided into smaller rooms.
The lowest floor is the two main vaults, about 30X40 each.
The office floor is being made into fancy offices, each with a safe/vault.
The second floor is now a wine cellar divided into private sections, each for rent; a hair salon (in a vault); and a cold storage vault (cigars?).
The huge vaults on the lowest level are now a small movie theater and a private party room.
The coolest thing there was in the equipment room. It has a 4' round by three feet thick safe door in the wall. When opened it shows BIG bars and a tunnel. It opens/closes the ventilation to the 3 underground floors. When everyone left at the end of the day, the safe door was closed and the time lock would not open until 5AM the next day.
