A regular 17-gon (heptadecagon) can be constructed with a straight edge and a compass.
Carl Friedrich Gauss proved this in 1796, at the age of 19! I used Geogebra for the construction.
Youtube Channels

Numberphile Sixty Symbols Periodic Videos Objectivity


Spiked MathGauss Factsxkcd Math Fail Frank and Ernst - Math


The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography by Simon Singh

Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem by Simon Singh

Flatland: A Romance of Many Dimensions by Edwin A. Abbott