We landed in Frankfurt more or less on time at Concourse C, where we waited for a US Airways plane to get out of our way. Then we got on a bus, rode - it seemed - all the way across the airport to Concourse B where we ascertained that our flight to Amsterdam was leaving from Concourse A, and, in theory, was already boarding. Then ensued one of those heart-pounding hikes of a few kilometers to our gate - not only through tunnels like this, but up and down stairs (or you can wait for elevators.) By some miracle, we didn't have to go through security again, which happens in Frankfurt and is particularly annoying when you have to give up or drink the water you just bought...anyway, that was not the case this time.