When you look at the Eurail Pass list of countries you may notice that Monaco is not included in the list. So can you visit Monaco on a Eurail Pass? Yes, you can. Monaco is a so small that its railway is served by France’s national railway SNCF.
[Monaco Montecarlo Train Station]
There is only one train station in Monaco (Monaco Montecarlo) which is on the Nice-Menton-Ventimiglia railway line. There is only 1.7 km of track in Monaco, and much of that is in a tunnel.
Like the rest of Western Europe, you will not pass a border control here, so no Monaco stamp for your passport, but if you get off here you can at least say that you have been to another country.