This series is based on a set of light novels which are also terrific and award winning, I haven't gotten around to reading any though personally. The anime follows several events which appear to be unrelated, different times, places and characters, but they are all part of a much larger story.
All of the many, terrifically constructed characters in this series are linked together in some way and their stories all tell the tale of something long in the past, a story about immortality, alchemy and survival.
In this anime there is a lot of blood and fighting, especially being centered around the events on the train The Flying Pussyfoot where mafia groups and even the mysterious rail tracer are on board.
This anime has a very "old gangster" vibe to it and I found this terrific. There are events such as shop shootouts and gang initiation fights and the classy music just backs it all up.
The interesting thing to note about the characters of this series is that they are all amazingly constructed, it is so that there are a lot of main characters, all tied together by the hilarious Isaac and Miria.
So I suggest checking it out, it's such an expansive universe and with amazing characters and fight scenes, not to mention a terrific feeling of everything-being-related, it's worth a watch. By the way, if you feel the anime is a bit slow in the first few episodes, please stick through it, it gets better.
Check out some more information at Wikipedia or at MAL.
PS. Happy Easter.