Pyramid at Giza // This was grand even for the gods who ruled ancient Egypt. Around 2590 B.C., Pharaoh Khufu conceived the largest-ever pyramid. Archaeologists estimate that 20,000 to 30,000 workers spent 30 years quarrying more than 2 million limestone and granite blocks averaging over 2.5 tons each. Workers probably moved the stones along ramps that stretched from quarry to building site, muscling them into place with ropes, counterweights and levers. At 450 feet tall, the pyramid covers seven city blocks.
Spruce Goose // With Nazi submarines decimating U.S. shipping during WWII, shipbuilder Henry Kaiser convinced eccentric aviator and filmmaker Howard Hughes to build a "flying boat" to ferry troops and war matriel over the Atlantic. Perfectionist Hughes was initially reluctant, but after parting ways with Kaiser he fell in love with the challenge of building the biggest aircraft ever. His creation -- which he finished in 1947, too late to aid the war effort, and paid for in part out of his own pocket -- was wider than a football field. It was made of wood (there wasn't enough wartime metal to waste on an unproved design); hence the nickname Spruce Goose. Hughes flew the plane once, for a mile; it now resides in an Oregon museum.
Missyplicity // Machines aren't the only things open to vanity engineering. In 1997, news of the cloned sheep Dolly inspired Arizona entrepreneur John Sperling to launch a multimillion-dollar effort to duplicate his spayed Siberian husky mix, Missy. The Missyplicity Project -- which spun off into a business for preserving pet DNA with a view to cloning the animals -- faced hurdles unique to dogs, such as the fact that their eggs mature in the oviduct, not the ovaries, making harvesting dicey. The project twice created cloned embryos, but the pregnancies didn't go to term. Missy died in 2002; Sperling hopes to duplicate her posthumously.
Gates Mansion // The Microsoft mogul's 66,000-square-foot home near Seattle is a (pre-wireless) embodiment of the complex Windows-based world he rules. As people move from room to room, temperature, onscreen entertainment and music adjust to tastes. Fifty-two miles of communications cable crisscross the Windows NT-run estate.