Chicago, IL: then and now

4 real landmarks in Chicago, each with an old photo you can fade into today's view. Find four landmarks in and around the Loop. At each one, check in to earn its badge, unlock its story, and collect a Time Card. Do them in any order. Everything stays on this phone.

• Cloud GateA giant mirror bean. Everyone calls it something else.
• The RookeryA building named for a pigeon-and-politician nest, with a Frank Lloyd Wright lobby.
• Buckingham FountainA wedding cake for a lake.
• Lincoln Park ConservatoryA glass-house jungle in the middle of winter.

Written from sources; not yet walked on site unless a stop says otherwise.