Conversation so far:
where is the bridge that turns into a tunnel
The Chesapeake Bay Bridge–Tunnel is a bridge–tunnel crossing at the mouth of the Chesapeake Bay, the Hampton Roads harbor, and nearby mouths of the James and Elizabeth Rivers.
what state is the chesapeake bay bridge-tunnel in
The Chesapeake Bay Bridge–Tunnel is in the U.S. state of Virginia.
how long is the chesapeake bay bridge-tunnel
The Chesapeake Bay Bridge–Tunnel is a 17.6-mile bridge–tunnel crossing.
why was the chesapeake bay bridge-tunnel built
The Chesapeake Bay Bridge–Tunnel replaced vehicle ferry services that operated from South Hampton Roads and from the Virginia Peninsula since the 1930s.

Question: when was the bridge-tunnel built
Self-contained rewrite: when was the chesapeake bay bridge-tunnel built