Of course, you can travel to Iran and through Iran by train. The easiest way is to get to Istanbul, which is possible from almost everywhere in Europe. Once there, just get a ticket to Tehran. The train is quite decent and cheap.  In recent years, the Iranian railway has expanded a lot and now you can travel to many cities by train. Tehran- Damascus is another route you may like to take. Soon the Iranian railway is going to connect to Pakistan railway and traveling to East Asia will be possible soon perhaps in 2011.