I know that the Catholic Church says that as Catholics we cannot divorce and remarry.  But is it true that it will be allowed as long as my first marriage was not held at a church?  I was married in a little "hole in the wall" when I was 18. I was divorced when I was around 27 yrs. old.  I am now 44 yrs old and would like to get remarried. Can I remarry as long as it is held at a Catholic church?

It sounds like your first marriage was invalid because you did not get married in the Church in the presence of the pastor of your parish and at least two witnesses.  I also assume you did not get a dispensation from such lack of “canonical form.”  However, when you go to your local parish and explain the situation, your priest will ask some questions such as “did you have any children in the first marriage?”   He will encourage you to reconcile with your first wife, especially if there were children involved, because divorce usually harms the children.
 
It is likely that you and your first wife will not reconcile.  At age 18 you were old enough to marry, but you might make the case that you were too immature.  Now at age 44, perhaps you have grown up and realize that marriage is not about you, not about your wants and desires, but about something larger: another person.
 
If you think you can keep your promise to “love her and honor her all the days of your life”, then you should pursue a declaration of nullity of your first marriage through your parish, and then get married in the Church.