Besides JFK and MIA, PAN AM had a hangar at LHR (on the south side of the field where Terminal 4 stands today) and a smaller facility at LAX. PAN AM Express planes had maintenance facilities in PNE while the German operation (I.G.S). had a hangar at TXL, including a mock-up for PAN AM crews‘ safety training. At Frankfurt’s Rhein-Main airport PAN AM used an own hangar.
There was a PAN AM facility at SFO as well, but that went to UAL along with other facilities when the PAN AM Pacific division was sold in 1985.
There was a smaller PAN AM hangar at SEA until the early 1970s. It was sold back to the city, who refurbished it into two additional gates on the original Concourse A. That structure was abandoned in the early 2000s when today’s Concourse A was constructed.
PAN AM also had some other facilities including crew base building spread around the SFO airport.
Going back further, PAN AM had hangars at HKG, HND and SAL (the original Ilopango airport), those were all more for line maintenance and they did not survive long into the jet era. Monrovia (in Liberia) was Pan Am’s primary port of call in west Africa, and kind of line operation there as well.