Is there anything separating the vultures from the visitors? Is that very common in European zoos? I'm not sure that I've ever seen a walk-through vulture aviary in a North American zoo.
Yes, vultures walk-through aviaries are quite common in Europe (Zlin, South-Lakes, Doué, la Barben, Bad Mergentheim, Les Abrets, ...) and generally, walk-through exhibits (for various species) are more common in Europe than in North-America !