When the autumn winds finally stripped the New York City trees of their more stubborn remaining leaves, I found myself thinking about my favorite green spot in Madrid, the last city I called home. Completed in 2008 by French botanist Patrick Blanc, together with Swiss architects Herzog & de Meuron, this 78 foot high vertical garden incorporates 15,000 plants of 250 species that are still thriving in the center of the city. Artfully arranged to be a living painting, the green wall helps to cool and filter the air around it, while creating a beautiful visual counterpoint to the oxidized iron cladding of the adjacent CaixaForum museum. It is a green design moment to be considered and enjoyed by those walking in Madrid’s cultural district, as well as by those of us already daydreaming about the return of Spring.