I crossed it recently on my worn out but functional bicycle, to go from where I had to be in France to a cute touristy village in Italy (it was a lovely ~80km ride)
I saw a shinny Ferrari being pulled over as I entered Monaco. (he probably thought he was some f1 driver in the tunnel) On the other end of the small country, a cop saluted me when I asked directions, then blocked the road to let me cross safely.
Only in Monaco.
(I also happened to have asked directions to a French cop earlier, and he wasn't as classy. And riding a bike in the surrounding area in France is very dangerous, because of angry car drivers) I plan to come back to visit the museums, and to go to the stadium.