Between 1963 up to the mid-80's the "American Folk Blues Festival" was an annual event that toured many of the blues greats around Europe (UK, Germany, and Scandinavia mostly).
Some the main stars include Muddy Waters, T-Bone Walker, Sonny Boy Williamson, Sonny Terry & Brownie McGee, Willie Dixon, Otis Rush, and many others.
I have a few DVD's of these shows (from 1964-65) and they are simply great to see.
Here's what a collage of the live video looks like:
And I picked a few posters of those concerts for your enjoyment (all taken from Wirz.de):