Where to look for a copy of a marriage license?

I am doing a family tree on my husband's side of the family and am in desperate need to obtain a copy of marriage license of his great-great-great-grandfather. There is some speculation that he was married more than once, so it will be fascinating to see how many marriage licenses we will find with his name on it. Can someone point me in the right direction?Where to look for a copy of a marriage license?
Do you know what state he was married in? It sounds like you are looking for something that is very old, but if you can find the state he was married in and the name he went by, then you can contact their vital records department and see if they may be able to lead you to a copy of his marriage license. If you can easily get to that state, you can actually view it for free, but if you want a paper copy for yourself, it will cost you a bit of money. Since you are doing such an extensive project, have you ever thought of using an online data base it find your information? They have some really good ones out there now that can find everything you're looking for a small fee. Try www.recordssitereviews.com to find even more information on your husband's great-great-great-grandfather. You can see his criminal record, birth certificate, where he has lived, any other names he has gone by, and even his driving record. Very thorough and very accurate. You should check them out. It would save you a lot of sleuthing.