World's Tallest Building

The was one of Phineas and Ferb's Big Ideas. It was meant as a "really big tourist attraction" for the city of Danville.

Inspiration
While watching a TV commercial begging people to come to Danville, Phineas decided that what Danville really needs is a big tourist attraction. Almost immediately after, he and Ferb came up with the idea to build the.

Construction of the building
Phineas and Ferb used various unconventional devices and procedures to build the. These included: The boys did not stop building until they reached the moon.
 * Firing RSJs using catapults and massive crossbows
 * "Dealing out" metal and glass sheets to make walls
 * Using elephants as workers
 * Fold-out structures
 * Walls made of confetti streamers that came out of a mechanical gorilla head
 * Statue of Venus as a foundation
 * Solar system model as foundation
 * Cube that folded out to form three floors
 * Balloon as a floor

Notable floors
The  had many unusual floors, many of them most likely serving as only tourist attractions.
 * Chess floor
 * Medieval renaissance fair floor
 * New-in-box action figure floor
 * M.C. Escher floor
 * One floor that they sublet to a small business
 * Rubber ball floor
 * Barnyard floor
 * Studio audience floor
 * Hundreds of floors without any oxygen

Aftermath
Meanwhile, Heinz Doofenshmirtz was trying to eliminate the full moon to make himself the most evil man in the Tri-State Area by rotating the dark side of the moon towards the Earth. This rotation was unsuccessful, only succeeding in removing the from Phineas and Ferb's backyard.

Appearances and References

 * "The Doof Side of the Moon"
 * "The Mom Attractor"
 * "Cranius Maximus"