A ‘Wall Dogs’ is an artist who hand-paints huge, photorealistic advertisements on the sides of buildings. It’s also the name of a Los Angeles-based company that paints larger-than-life ads for movies, cars and sportswear, some over 20-stories tall. Owner Riley Forsyth, a 40-year veteran of the trade, tells Bloomberg how the process works and why this low-tech method is still in demand.

High-Rise Magic: How a 23-Story Ad Gets Hand-Painted

High-Rise Magic: How a 23-Story Ad Gets Hand-Painted [VIDEO]