The photograph shows the interior roof line of the San Felipe de Jesus Church, Cuernavac, Mexico. It is of particular interest because although the surface is curved, we can see the straight imprints of the timbers used in forming the shell.
There are several curved surfaces which contain straight lines within them. We might think of circular cylinders and cones, although these seem a little trivial. Another such surface is the hyperboloid of one sheet which contains within it two sets of intersecting straight line generators. (See Photo #12.) The surface shown here is technically called a hyperbolic paraboloid. It also has two sets of interesecting straight line generators. It has the shape of a saddle. There might be a church or building near you which has a roof of this shape.
http://en.wikipedia.org/wiki/Paraboloid
