They used to suggest 8 yrs old (I think), but I am sure that ABD can fill you in on that. I would imagine it would depend a lot on which tour you plan on taking. I took my 9 yr old last year and she was just great! I do know that a 5 or 6 yr old was on the tour and I don't think she got too much out of it - plus there was a LOT of walking and her dad had to carry her a lot. On the other side of the coin, we had kids up to the early 20's and all enjoyed it very much.