Oldest Book in Your TBR Pile?

In my TBR shelves, I've got historical romances from Kathryn Smith, Susan Squires's Danelaw, many, many Barbara Hamblys, and some random paranormal books I picked up from conferences.
At least I know I will have a book I haven't read up until the day I die.

Being a military family that moves every few years, I've had to pare down my stuff to the minimum. I have books that complete collections which I haven't read, (I will someday, I swear!) The oldest is "Falling Free" by Louis MacMaster Bujold. I also keep a notebook with a list of books I wanted to read but never got around to it. With the advent of e-books, it's becoming easier to imagine a near future when I'll have the budget and leasure to download some of these and get to them.

@Megan, I have Danelaw in my TBR pile, too. Oldest honors, though, have to go to Sweet Savage Love.

I think my oldest book in my TBR pile is Where Serpents Lie by T. Jefferson Parker that a friend gave me back in the mid-90's . I remember reading a few pages but then never picking it back up again (probably because it wasn't a romance book). I've kept it though because it looks like it a good story (and I have a hard time letting go of stuff). I also have a couple of books from 2005 that I started/skimmed. Prior to 2005 I never had a TBR pile. Now I have over 300 books in the TBR pile. Does it count if I skimmed the book? Because then probably half of that pile has been partially read.

When Atlas Shrugged. I so want to read it but never quite get to it.

@njoireading, When Atlas Shrugged is on my TBR pile as well, but I only bought a copy a couple of years ago. So far, I haven't found the time, but did see last year's movie (Part 1 of 3, next due out just before November).

Most of my oldest TBR entries are science fiction or fantasy bought somewhere between 1975 and 2000. I'm currently in the process of weeding them out (I have NO shelf space). If I don't think I will EVER get to the book, it needs to grow legs to reach someone who will. I'm donating such culls to my local library (for fund raising sales), Goodwill, or a local used book store.

Angel at Dawn by Emma Holly, my mom actually gave this one to me because she realized she already bought it, I know there are other books before this one in the series that I haven't read yet and I hate starting a series in the middle, so thats the reason it's on my TBR pile.

According to PBS, my oldest is Seaswept Abandon by Jo Goodman. I like Goodman a lot... but it seems like there are always new historicals to read. For a while I was reading the oldest books on my TBR in order, but I've been too busy with netGalley books and review copies and expiring library ebooks... and I'd almost always rather read an ebook than paper, now. Quite a few of the old ones I started and realized I really didn't want to read, after all, so out they went, yay!