I love tunnels! Last Sunday we had a convoy of six MG ZS's on the way to Duxford for a show. The traffic got backed up as we were 'playing'.
Rules are windows down, stereo switched off and enjoy
My commute can easily take me via the new tunnel on the A3 at Hindhead, I'll let you know how that is once the traffic has calmed down abit. Never driven across europe so can't comment.
There is the Chesaspeake Bay Bridge-Tunnel crossing Virginia and Delaware that spans 17.6 miles. Not done that as yet but will the next time I go there.