I did it at age 27. There were a few times when I’d have liked some company, but mostly it gave me the freedom to do what I wanted. It was a much more satisfying trip that way than it could have been if I’d been constantly negotiating with someone.
For instance, I didn’t want to go shopping at all. I wanted to visit museums, as many as I could manage, and major spots such as the Tower of London and Anne Frank’s house. Later on, traveling with friends, I did have to make some unwanted compromises. Because of course they did want to go shopping.
What I did that first time, and would be happy to do again, was to book a tour that handled travel among selected cities, customs assistance, transfers, and hotels, gave me someone to call on for help with things like reservations, and arranged a bus tour of the city for the first morning at each destination. I was then on my own, after getting a feel for each location. This allowed me to get oriented with the help of a guide and then spend my time on what interested me.
Oh, and the tour included event tickets for one program (theatre, music, dance) in each city.
Experienced travelers may scoff at the idea of booking a tour, but I was not an experienced traveler, and I had no companion. For me the structure gave me confidence with all the details I’d have been anxious about. It freed me to use my independence as far as I was able, with a safety net. I could also find mealtime company among fellow group members when I didn’t want to dine alone.
Reminder: Do your homework first on anyplace you plan to visit. Don’t wait until you get there to ask, “So, what should I see?”