This article covers the Iranian city, for the Russian railway line see: Baikal-Amur Mainline.
There are plans to extend the Train line from Tehran to Bam
The city stretches out a lot so you might want to use a savari to get to the arg.
The ancient citadel of Arg-é Bam probably has a history dating back around 2000 years, to the Parthian dynasty (248 BC-224 AD), but most buildings were built during the Safavid dynasty. The city was largely abandoned due to an Afghan invasion in 1722, which ended Safavid rule.
The main attraction, the ancient citadel of Arg-é Bam, suffered badly in an earthquake in December 2003. Today little is still to be seen and access is extremely restricted; there is only one main access path still open to the public and the castle on top of the hill is out of bounds.