The Great Pyramid of Giza, the Colosseum, the Great Wall of China, the Notre Dame Cathedral. What would it take to build these remarkable super structures today? How long would it take? How much would it cost? How many workers would we need? In our modern era of glass and steel, could we even pull it off? If We Built It Today talks to architects, historians, engineers, and builders to find out if we could use modern day innovations to recreate these iconic masterpieces, or if fundamental techniques have been lost to time.