AARP would be virtually useless in Europe. You are already entitled to discounts as a senior and all you need is proof of your birthdate. In SOME, not all, countries.

Italy used to have senior discounts, but only for EU citizens. Now they don't offer them at all.

"There are no age restrictions on joining AARP,"

You have to be at least 50 and that's too young for most senior discounts.

The first time I got an OAP (Old Age Pensioner) discount was at Dunluce Castle and I didn't ask; the kind gent behind the register gave it to me based, I assume, on my white hair!

What bettyk said ... many venues offer "concessions" to Seniors .... museums, castle sites, gardens, etc. We have taken advantage of this over the last few years in France, Germany, Scotland, Spain and Portugal. All you need is a photo ID showing date of birth.

Most provide the discount, usually 10 - 15%, at age 65, but some provide it at 62.