Yesterday evening I was at the opening of the Man Ray exhibition in the Max Ernst Museum in Brühl, Germany. It was very interesting. The exhibition is very well conceived and shows the beginnings of photography as an art form in the early 20th Century. The most exciting thing for me was to learn about how Ray's photographic techniques developed (e.g., the rayographie and the solarisation), and how he has encountered some technique purely by chance. For photo enthusiasts, the exhibition is worthwhile. It runs between the 15th of September to the 8th of December 2013. Apart from the Man Ray exhibition there is still the permanent exhibition of Max Ernst, which is also worth a visit.
Link to the exhibition details (sorry, available only in German)