  A symmetric Venn diagram is one that is invariant under rotation, up to a
relabeling of curves. A simple Venn diagram is one in which at most two curves
intersect at any point. In this paper we introduce a new property of Venn
diagrams called crosscut symmetry, which is related to dihedral symmetry.
Utilizing a computer search restricted to crosscut symmetry we found many
simple symmetric Venn diagrams with 11 curves. This answers an existence
question that has been open since the 1960's. The first such diagram that was
discovered is shown here.
