This is one of the reasons I did my double-Atlantic trip the other week, because I remembered how hard it was for me to find "ground level" for PNF the first time and I was sure my husband, with two kids in tow, would have trouble too. Sure enough when I announced "now we have to go to ground level" all three of them insisted we were already AT ground level. I just led them to the semi-secret elevator (not all the elevators in that area go down) and then we were all set.

PNF has lots of signs on their buses about this but none that clearly say "you need to go DOWN to ground level." It looks like ground level when you look out the windows, so you figure you're good. The first time I made a ticked off call to them since I couldn't find post whatever-I-was-supposed-to-be-at and a patient PNF person convinced me to go back inside and go down.