There is a better version of the "mountain fortress" graphic and a description of how this "fictoid" became established here, including this quote from NBC's "Meet the Press" when Rumsfeld claimed that ... there's not one of those. There are many of those.

Russert: The Times of London did a graphic, which I want to put on the screen for you and our viewers. This is it. This is a fortress. This is a very much a complex, multi-tiered, bedrooms and offices on the top, as you can see, secret exits on the side and on the bottom, cut deep to avoid thermal detection so when our planes fly to try to determine if any human beings are in there, it's built so deeply down and embedded in the mountain and the rock it's hard to detect. And over here, valleys guarded, as you can see, by some Taliban soldiers. A ventilation system to allow people to breathe and to carry on. An arms and ammunition depot. And you can see here the exits leading into it and the entrances large enough to drive trucks and cars and even tanks. And it's own hydroelectric power to help keep lights on, even computer systems and telephone systems. It's a very sophisticated operation.

Rumsfeld: Oh, you bet. This is serious business. And there's not one of those. There are many of those. And they have been used very effectively. And I might add, Afghanistan is not the only country that has gone underground. Any number of countries have gone underground. The tunneling equipment that exists today is very powerful. It's dual use. It's available across the globe. And people have recognized the advantages of using underground protection for themselves.