In movies, the hero will do everything they can to avoid the villain's lair, some overly elaborate space that the bad guy uses for devising horrible plans and housing ostentatious art and modernist furniture, only going in if the world/someone really attractive is under threat.
For we non-heroes, these palaces of evil are places we want to see. Here are a few you can technically go and look at*.
(*In most cases you'll need enormous amounts of money and dogged determination. These are also key attributes in becoming a movie villain.)
(Images: AllStar, Rex)
In the film: The Manhattan Museum of Art
In reality: US Customs House, Bowling Green, New York, USA
Vigo the Carpathian is resurrected from a painting in the bowels of this grand museum. He doesn't do much plotting or stalking of the lair himself, instead leaving that to his presposterously accented acolyte, Janosz. Is eventually defeated on his own turf with some souped up fire extinguisher things.
In the film: The GoldenEye Satellite
In reality: Arecibo Observatory, Puerto Rico
In the seventeenth Bond movie this giant satellite dish is part of fallen agent Alex Trevelyan's scheme to pull off the most elaborate bank robbery in history. In the real world it's a remote telescope used in astronomy research. You can't really just rock up and start with your 007 impression, but if you'd like to submit a proposal for why you need to use the facility for astronomic research purposes then you never know your luck.
In the film: Norman Osborn's Mansion
In reality: Tudor City Apartment Complex, East 40th Street, New York, USA
The giant home of Norman Osborn/secret lair of the Green Goblin, requires a huge amount of real estate that's difficult to find in New York. So the filmmakers used a building that actually houses a large number of apartments and imagined it all belonged to just this one mad billionaire. You can't go inside unless you know someone who lives there, but you can see it from the street - and since only the exterior was used in the film then that should be enough.
Quantum of Solace
In the film: Dominic Greene's hideaway
In reality: La Residencia, Paranal, Atacarma Desert
Another Bond lair (lot of lairs in Bond) and another scientific facility. This time it's the desert getaway of conjurer of confusing water-based plots, Dominic Greene. Like the lair in GoldenEye, it's actually an astronomical observatory. The building shown in the film is the residential area, constructed for workers to get away from the punishing heat of the desert. You'll need to become an astronomer with a decent tolerance of UV rays in order to visit.
In the film: Arkham Asylum
In reality: National Institute For Medical Research, London, UK
Maybe not a lair as such, but it's home to most of Gotham City's villains at one time or another. The exterior for the insane asylum is a medical research centre in Mill Hill, but that internal staircase where the police force is attacked by bats is actually the grand staircase of the St Pancras Hotel, by St Pancras Station. This was, of course, before it was renovated to become a very fancy hotel. You can stay there if you've got the cash - or, more economically, go for a drink in the bar and sneak out for a look at the stairs.
In the film: Stryker's base at Alkali Lake
In reality: Peter Lougheed Provincial Park, Kananaskis, Alberta
As you can imagine, the interiors for Stryker's lair were all built on soundstages, but if you want to see the dam under which they're housed in the film then head for the dam in this picturesque park.
Harry Potter and the Deathly Hallows
In the film: Malfoy Manor
In reality: Hardwick Hall, Derbyshire, UK
The home of Harry Potter's Malfoy family is less spooky in real life. In fact, if you wonder why it looks a bit different than it does in the films that's because there was some digital jiggery pokery to make it look more imposing, adding some pointy roofs and the like. It's completely open to the public so go and have a poke around.