Lavoir in Tamnay en Bazois.
A 'lavoir' is an old public washing place. We saw several in Burgundy, France.
The picture was taken in bright daylight, as can be seen in the upper image.
I wanted a more dramatic look so I switched my camera to manual and underexposed the image. I then put my 580EXII in the lavoir itself, using it to illuminate the interior. I controlled the falsh with my 7D, using its built in wireless controller. Quite easy to change the power of the 580EXII as long as its sensor is pointing towards the camera. The result is the middle image.
Finally, in Photoshop I increased the brightness of the roof a little. In hindsight I also could have done that using the 7D's built-in flash while on site. But, as an excuse, there were 10 people waiting for me so I only had a couple of minutes.
The final result is here: www.flickr.com/photos/marcverdiesen/6571064277/