Hit the space-bar to switch between auto-move and user-controlled modes.
Click the picture, then hold the left mouse button down and drag your mouse to move around the virtual art gallery.
Click on a picture to see a close-up view, click again to return to the castle view.
If you can't see the 3D gallery at all - download the Shockwave player here

If the interactive shockwave file is not working for you - here is a video of the gallery.