Mrs. Stone Goes to Rome - How does she do it?

This is a post about what happens when you want to travel and your better half doesn't because:

1. You don't have one. You never had one, or he/she is long (or short) gone, or (sad to say) deceased;
   
2. Your partner has no interest in the places and things that appeal to you. In fact, it's his highway or no way when it comes to travelling;
   
3. He/she simply can't get the time off.

So what do you do? I'm asking this for a reason; specifically because I've answered #1. I'm mate-less and I've got wanderlust. But I'm also somewhat trepidatious about the whole single woman traveling alone thing. I'm going to start researching (that's what we ever-grad students do) the topic. Will you help, please.

Send along any sites, stories, suggestions about traveling alone when you're a mid-life woman. That last modifier is the important one. I know what it's like to travel alone when one's in one's twenties and thirties. I've done it and had the requisite adventures. And I'm sure that there are various tours for elders that are gentle and protected. But for those of us who are between those two poles, what can we expect? what should we look out for? where should we go--and how?