There is no age limit to travel, luckily. Some people have medical issues or family responsibilities that limit their ability to get around as they get older, but in fact that can be a reality at any age.
It is good to know that a lot of people keep on travelling into their senior years, and some actually become what it politely known as "location independent" or nomadic, moving from place to place as the spirit moves them, or the authorities move them on.
I have written previously about one or two such people who maintain blogs, and recently discovered another pair, Alison and Don (http://www.alisonanddon.com.) http://www.alisonanddon.com. They are a senior couple originally from Vancouver, BC who have been on the road for several years. They have visited a number of countries in Europe and Latin America, Southeast Asia and the Antipodes, and their blog is full of great photos as well as musings on both the outer and inner aspects of travel.
If you are wondering whether this lifestyle might be for you, check out their blog for information on how they manage this lifestyle despite the fact that one of them has significant health issues. Of course they both must manage things like investments, taxes and the usual business of daily living while on the road, and that can be a challenge even at home.