dome 7
The midpoints of the sides of the basic square are vonnected by ribs. They create a second 45° rotated square as base for a second dome.[br]
foto: [url=https://www.flickr.com/photos/100759833@N05/albums/72157649417564427]Santiago Lopez-Pastor[/url]
In the applet below you can see how such a configuration looks like in 3D.