### Quick Answer

**A dodecagon is a two-dimensional shape with 12 sides.** A regular-shaped dodecagon has all its sides with the same length, and all internal angles are the same size. An irregular-shaped dodecagon has sides and angles of different sizes.

### Full Answer

A dodecagon also has 12 vertices and 12 internal angles at each one of those vertices. The internal angle in a regular dodecagon is 150 degrees, making the total sum of angles 1,800 degrees. Many historic buildings have been built in the shape of a dodecagon, including the Vera Cruz church in Segovia, Spain, and the Torre del Oro, a 13th century military watchtower in Seville, Spain.