I had one many moons ago where I had to go to the CEO's second home in Paris to fix his home WiFi, so off I go onto the Eurostar, traipse across Paris and find his amazing 'apartment' (floor of a huge building) and see his hilarious outdoor WiFi antenna (complete with lightning arrester) and he's there complaining it's got no range. As I test I find it's an amazing signal, walk down the corridor still amazing, then all of a sudden it drops to zero. Confused I look up and see I'm now in line of sight with a large window and filling the view out of that window is the rather large transmitter (bit bigger than his router and even his outdoor antenna in the hallway) - the Eiffel Tower. Then he proceeds to tell me taxi's radios don't work here either and even TV/radio is hit and miss.
Not much I can do apart from tell him try installing cat5 everywhere and put at least one access point in every room on that side of the property!
I was on holiday in Dublin a few hours later so three capital cities in about 12 hours.