Phineas And Ferb: Season 4, Episode 29 - ProjectFreeTV

4 - 29: Steampunx

When Phineas and Ferb discover a commemorative coin from the 1903 Danville World's Fair, Lawrence recounts the events of the festival to them, in which steam-driven devices were introduced and a set of kids, who were very much like them, were preparing for the highly anticipated event.