Technically this isn’t a sketch maybe, still I drew this is under 3 hours. It is the Roman general Pompey, who forged the first triumvirat (a pact of three powerful men) with Caesar and Crassus during the first century bc. :p I drew him because of his recognizable portrait. Also I wanted to practice folds. Since I studied Ancient Cultures, I’m thinking of combining this knowledge with my current knowledge of drawing and make a series of portraits of famous and less famous historic figures. We’ll see how that goes 
(thumb shows full size image)
