<blockquote>The 80-acre green space is the Buitenschot Land Art Park. Its trenches and ridges hold bike paths and sports fields, but these recreational features are a bonus. Its main purpose is to deflect ground noise, the low-frequency drone that planes make when they take off and land.</blockquote>
via <a href="http://www.smithsonianmag.com/innovation/crazy-land-art-deflects-noise-from-amsterdams-airport-180955398/?no-ist">This Crazy Land Art Deflects Noise From Amsterdam's Airport | Innovation | Smithsonian</a>.