It's an epic historical(ish) fantasy. There are four novels in the series, written at least five years ago. Each novel takes place in a different time period - the first book was pre-medieval times, the last was closed to modern day (1960-70s). Each book took place around the same physical location that becomes a well-known modern city. The basic premise of the story was that a small group of characters were struggling to control a hidden, powerful labyrinth. All of them initially failed, but their souls and those of several other involved family members became caught up in the conflict through some ritual magic and were destined to be reborn in the future to continue their struggle - the 2nd to 4th books were of them in different lives recalling their past and being drawn together again into the same city and battle. There was a lot more character development than actual fighting, though, and by the final book they mostly banded together to destroy a malevolence coming from the labyrinth rather than control it. This is bugging the heck out of me lately, so if anybody knows the name of the series or any of the book titles I will be stupidly grateful.