Going to be in Frankfurt for 5-6 hours (long ass connecting flight to Japan), so thought I'd check the city out.
Anyone been/live there? What's the best area(s) to take some photos?
I wouldn't recommend straying too far from your airport to be honest. Typically you need about 2 hours to catch a flight properly after checking bags, going through security, and boarding the plane (could be less since you're connecting but still).
Especially since you'll be in a city you don't know and you could easily get lost on mass transit, or get stranded due to some sort of delay, or robbed. By all means wander around a short distance but you're probably not going to get in a nice trip/take any meaningful shots during a layover.