This is the green wall at Dansko's less-than-a-year-old corporate HQ in West Grove, Chester County. It's a haul from Center City but what a cool place to work. The wall is 22 feet high, 20 feet across, in the 2 1/2-story atrium. It's planted with tropicals and incorporates this beautiful waterfall. The wall embodies some new technology that is just taking hold in this country. Called a biofilter wall, its plants absorb carbon dioxide, pollen and all sorts of bad stuff in the indoor air (toluene, formadehyde), filter it through soil-less roots and shoot it into the building's HVAC system. It ain't cheap, and it's unclear how much actual benefit employees derive as measured by cleaner air, but aesthetically it's a wonderful sight. And it makes for a very pleasant work space. Dansko has three green roofs and just about every amenity possible, including onsite child care and a very nice gym, to make going to work less stressful. (These days, I can only daydream about a workplace like that.) Watch for a story in the paper on Friday about green walls. There are lots of them - green walls, not stories, which is what made it so hard to do. You'll be surprised how easy some of them - not this one, obviously - are to put together. Even so, you might want to take a ride out to West Grove. Strictly business, of course, but while you're there, no harm in checking out the Dansko shoe outlet!