In geometry, a rotunda is any member of a family of dihedral-symmetric polyhedra. They are similar to a cupola but instead of alternating squares and triangles, it alternates pentagons and triangles around an axis. The pentagonal rotunda is a Johnson solid.

Set of rotundas
(Example: pentagonal rotunda)
Faces	1 n-gon 1 2n-gon n pentagons 2n triangles
Edges	7n
Vertices	4n
Symmetry group	Cnv, [n], (*nn), order 2n
Rotation group	Cn, [n]+, (nn), order n
Properties	convex

Other forms can be generated with dihedral symmetry and distorted equilateral pentagons. ^{[example needed]}