I stumbled over "Cities of the Underworld" while browsing around on Youtube and I was hooked right from the beginning. What a great show this is. Both hosts in my opinion do a really great job by doing their spelunking trips with a lot of fervor and enthusiasm and you can tell the people they talk to are getting excited as well, so their enthusiasm seems to be quite contagious. Some of the scenes are a tad over the top ("We are the first ones going down here, so we do not know what we will see" or the one in Berlin where the host enters for the first time a bunker on his own), but so what, no damage has ever been done by some showmanship. I myself have been in some of the described caves and underground structures and from the few I have seen I have to say that the description given by the host is usually very accurate and reliable; so while it is mainly good fun to watch the show, you might actually learn something from these shows. I can fully recommend this show and I can only express my misery of having not been asked to do this show. I would have done it for free :)