I’m pretty fit for my age of 55 and have a cute petite figure, especially from behind. (Fully Clothed Only!)
What happens on occasion on my walks is I will get whistled at and then the guy will see my face and get embarrassed when he sees I’m not young. Or then they’ll turn it in to a thumbs up. Either reaction gives me a chuckle. 
I haven’t noticed any lingering stares while out in public though.
This, with the addition of “as far as I can tell”.
One thing that I suspect (for both sexes buy maybe more predominantely among women) is that a person usually only lets their “stares” be picked up on by the focus of their attraction when they want them to be. So I think “as far as I can tell” should be an automatic disclaimer on all of these.
Younger and long-haired I got a lot of stares, if only to ascertain gender. A squarecut 20 years ago impressed me into the ranks of the nondescript: an unimaginative composite sketch come to life. If I noticed someone staring now—man or woman—my first impulse would be to check my teeth for spinach and my heels for toilet paper. Sometimes when I’m out with my wife I notice lingering looks that I take as incredulity. Things could be worse, the reassuring voice whispers, and will be soon.
I have to say that when I passed 30, I began to notice how beautiful people in their 20’s are. 
For what it’s worth: These days, if you find my gaze lingering on you (and this actually applies for both genders, boys and girls alike), my sad, longing stare probably doesn’t mean “I want you”, as much as “I want to *be *you”.
Hey–at least you had until your early 40s. I’m a 37 year old woman. I became invisible about 5 years ago.
I get looked at rarely, but when it happens, it tends to be pretty intense.
My mom said she noticed an interesting phenomenon when she reached ‘old lady’ age, which for her was a little after 60. People started seeing her again, but not as a sex object. Instead, young people, especially young men, started seeing her as something of a mother or grandmother figure. They sought her out for advice, and when she gave it, they listened.
Now that’s something I’ve yet to experience.
I don’t have any idea. I’m pretty oblivious that way.
Female. Often. I’m not particularly striking but I live in Italy.
It happens to me all of the time because I’m gorgeous.