Every episode of How I Met Your Mother is centered on the maturation of at least one character. In this week's episode, "Architect of Destruction," Ted meets Zoey (House's Jennifer Morrison), New York's busiest, most well-groomed activist. She's beautiful, blonde, witty, and also versed in architectural history, and Ted is immediately smitten. When she's not being arrested for stealing police horses at anti-war rallies, chaining herself to 100-year-old redwoods, or setting cars on fire at a Guns and Roses concert, she's stealing bunnies from evil cosmetics companies (apparently by herself), and leading a one-woman effort to save The Arcadian, a fictional New York landmark. The Arcadian also happens to be the planned site for the building Ted has been hired to build for Barney's company.
Ted spends much of the episode agonizing over the merits of the old versus the new and how hard to push for the preservation of The Arcadian. Barney provides a humorous counterpoint to Ted's glorification of the old, defending even the new Star Wars movies (due to a superior explanation of intergalactic trade laws), and the song "Chinese Democracy" (an indication of Axl's maturation as a songwriter). But it's only when Ted finds out that Zoey is actually married that he decides to just build what he wants. The realization, of course, is that Ted too often tries to impress his dates by molding himself to meet their interests, from extreme sports to Civil War reenactments. Thus had the girl never been involved in this instance, Ted would have just designed the building he wanted all along without any moral or ethical headaches.