Say what you want about villains, they have spectacular architecture. But they're also a nightmare to create — which is why we don't have more undersea bases or faces carved into mountains in real life. Here are the weirdest design specs of some of the most famous villain lairs.
The Death Star is a terrible symbol of the Empire's barbarity, but it's an absolute miracle of plumbing. To understand why, consider how much tubing and how many water tanks it would take to maintain water pressure for a small moon. Depending on how the artificial gravity is set up (some people say the gravity on the Death Star goes top to bottom, and some say the artificial gravity pulls towards the center of the ship), you would either need a giant water tank at the top, or lots of smaller water tanks located at regular intervals over the entire surface of the ship.
Artificial gravity wouldn't be the only kind of gravity people had to deal with. When the Death Star gets close to planets, and when it orbits them, their gravitational pull could mess up the plumbing in the entire ship.
Also consider what happens when the Death Star moves. Twirl a bucket of water in a circle and see what happens. The phenomenon happens in our own veins — pilots black out in accelerators because the blood drains away from the front of their body. The same thing will happen when the Death Star accelerates. Unless there is an incredibly strong pump that can keep the water moving through the ship despite the motion of the ship, all the water will "pile up" on one side.
Doctor Evil's Lair is carved into the side of a mountain in what looks like a beautiful tropical island. It's picturesque. It affords a villain the ability to look out from behind his own eyes, which is very cool. It's also a perfect location for a lightning strike.
Climbers and cavers are told that, as soon as they see signs of a storm, they should get down a mountain, and away from vertical cracks and shallow caves. The construction on Mount Rushmore and the Crazy Horse Memorial were repeatedly delayed by lightning strikes. Deeper caves are relatively safe, unless there are metal cables or support beams running from the rock's surface into the cave — in which case you are importing lightning.
Elevators and electrical systems in caves are regularly downed by lightning strikes, so if you want an evil lair in a cave, you're going to have to put a Faraday cage around everything even remotely important.
You know what you don't want at the bottom of a massive, enclosed hole in the ground? A pit that spews forth poison gases. You especially don't want one that's hot, because the heat will cause the gases to rise and fill the pagan-temple-slash-mine-full-of-child-slaves that you've built. And this is the problem with a volcano lair.
Oh, don't get me wrong. It looks cool. But it has to have the best ventilation system in the world to let anyone survive down there. At best, the magma pit is putting out a lot of carbon dioxide. It has to be pumped to the surface of the mine, and replaced with clean air from the outside, or everyone will suffocate.
(Pictured Above: Someone who would certainly already be dead.)
You'll also need a lab that continually tests and reacts to the volcano gases. For example hydrogen sulfide paralyzes nerves, including the olfactory nerve, which means people can't smell it after a few whiffs. Either it has to be continually filtered out, or the ventilation has to be even more aggressive to limit people's exposure. The fact that this lair has so many different levels, pockets, and hidey-holes means the ventilation system has to be exhaustive. Anywhere the gases could accumulate has to be flushed out.
I get it. Not every lair should be on an isolated island. Sometimes a villain wants a place with quick access to the surface of a city. And a sewer lair has a kind of deep dark urban chic.
But Gotham is a city with a port, and therefore is subject to high tides. It has a large population, and therefore is subject to "high flow" times. It has a snowy winter season, and therefore subject to rainstorms and sudden melts. So if you want to make a Penguin lair, you either need a hell of a pumping system in place, or a kind of "back flow prevention device" that can stand up to incredible pressure. Otherwise the place will regularly fill to the top with water. Or... something else.
Shipwreck City, in the Pirates of the Caribbean movies, is made entirely out of wrecked ships. At first it seems that making an island out of a biodegradable substance like wood is a recipe for disaster, but it has actually been done. The lochs of Scotland contain the remains of crannógs, small artificial islands that aristocratic families made by spearing the bed of lakes with sharpened posts, covering the posts with interwoven mats of twigs and reeds, and then heaping up mud and sand around the base of the island.
Shipwreck Island is possible, then, but the challenge for the designer is making it look bohemian, rather than precisely constructed. Sometimes villains require style as well as function, and need to maintain that pirate chic. Which means you need to turn found materials into the right materials. The masts and prows of ships are perfect for spearing the sandy bottom of a cove. Make matting from sails, and cover the matting and sand up with smaller wrecked ships.
Since this takes place in the Caribbean, it might be a good idea to let nature do the stabilization for you. Both the look and the stability of the island might be improved by encouraging the formation of coral around the foundation.
If you want to make an ice lair, you're going to need to get your hands on not just ice, but snice. The word "snice" comes from snow and ice mashed together. Snice is made by freezing precisely aerated water. When the weather is uniformly cold with no sunny days, usually thanks to a magical villain with control over the weather, snice forms the mortar between bricks of ice in the villain lair, gluing them together and making them stable.
When the villain has no magical powers, the lair will face sunny days. As we can see above, the lair will also face sometimes face lit candles, since villains will do anything for effect. Line the surfaces of the lair with snice. It makes an excellent insulating material. It reflects sunlight, keeping both itself and the ice beneath it cool and unmelted.
Underwater lairs, like Atlantis in James Bond's The Spy Who Loved Me, are surprisingly feasible. According to Ian Koblick, a marine biology professor and diver, we already have the technology to build underwater colonies of up to 100 people.
Unfortunately, if the supervillain wants to destroy the world and watch from their lair, there is a problem. Not only would we have to invent the technology to get the environmental controls of such a colony just right, such underwater lairs need to have back-up on the surface. There's no way to assure the safety of the inhabitants of an underwater base without having a back-up base on land, monitoring the atmospheric composition and able to quickly send supplies out in an emergency. So one secure base has turned into two secure bases, with a secure communication system between them.
High towers, like Isengard and Barad-dûr don't really present tough engineering challenges - although they do require elevators. The main problem is explaining to an insane, dictatorial villain that if he makes his secret lair a giant tower, he'll look like he's trying to compensate for something.