I'm surprised no one has identified the airframe, yet. The wing clearly isn't from a 787 (yes, I know, that part's easy), but is it a 767-something or 777-something? I'm not familiar enough with the finer details to know. Given the airframe, that would be a hint as to what airport it might be servicing. And given the identified livery of the other aircraft, FCO or MXP would make sense, but since the contrails are in all directions, a more central city served by UA might make sense, like FRA or maybe MUC.

But I bow to the considerably more talented folks here!