The Discontinuity Guide really did put it best when one or all of its three authors said this about City of Death: "Just when you think it can't get any better, John bloody Cleese appears." Cleese, who was busy making the second series of the greatest comedy programme ever created, Fawlty Towers, at the time, probably provides the straightest performance of them all in this story, oddly. A cameo from Cleese would appear so jarring in any other story in any other programme, but this is City of Death - a story which is so comfortable in writing its own rules in the process of shattering others that its brilliance is in its audacity as much as it is in its more corporeal elements.
The basic plot of this story actually bears a resemblance with that other effortless piece of perfection of the Tom Baker era, The Talons of Weng-Chiang. In both stories, a creature from another time/place is stranded on Earth and has to resort to scavenging the local surroundings for treasures (Magnus Greel needed the raw energy of young women, Scaroth needed the funds from stolen artwork) to try and recover a way to leave the planet, most likely destroying Earth in the process. Both stories are also the culmination of all that was great about their respective eras. Talons closed of the Philip Hinchcliffe/Robert Holmes era in fine style, while City of Death is the zenith of the brief time in the slightly more erratic epoch of Graham Williams and Douglas Adams that represented the best of all things Who. Never before or since had humour and drama mixed so well that it is unperceivable if you were watching the funniest comedy or the most dire drama.
City of Death, plain and simple, represents four episodes of the best Doctor Who ever made. It also wraps up in much the same way that it started, with a hint of whimsy and romance, and a scene that has most likely been reenacted by countless Doctor Who fans to the point of cliche. But I don't care. That last scene is so charming, just like the story as a whole, that, one day, when I go to Paris, I will make it a point to stand at the base of the Eiffel Tower, look up, and yell "Bye bye, Duggan!" at the top of my lungs. And it will take the assembled hordes of Genghis Khan to stop me from doing it.