Watch any of the “trash to treasure” shows populating TV lineups these days (you know the kind: Antiques Roadshow, American Pickers, it’s a long list) and you’ll know we love us some signs. And why not? The best of the lot combine striking design with sturdy, reliable function, and they can conjure a type of nostalgia for a time gone by, trips to far away lands, or just powerful visual cues that tell us we’re safe and sound where we belong…and at home. The really great ones keep getting better, as noted in Slate magazine's History of the Transport of London by Kristin Hohenadel. Anyone who’s ever taken the “Tube” knows these signs, steeped in classic Brit simplicity and timelessly hip. Check out Hohenadel’s story, then cruise through this cool map of all the art found in the city’s subway system. London calling, indeed.