These photos strike me as the same sort of thing as the famous (or infamous) "face" on Mars, which was nothing more than a trick of light. Mars rotates a hair in its normal day, changing the angle that the sun hits the bloody big rock, and the face disappears. Given a photograph of random geological debris scattered about (I'm not sure that "geological" is the appropriate word when talking about other planets) and if someone looks hard enough and uses their imagination a lot, I'm quite sure he could perceive a recipe for shrimp filé gumbo etched in the terrain (or a love note from Dejah Thoris).

As to the idea of hollow planets enclosing mysterious civilizations, the civilization would have to be very highly advanced to manage a feat of engineering like that. The reason that a celestial body large enough to qualify as a planet is in the shape of a globe (rather than, say, a cube) is that the gravity of anything over a certain critical size (mass) is going to crush it into a globe. The "hollow earth" stuff back in the Thirties (early days of pulp science fiction) that guys like Richard Shaver tried to pass off as real (but kept secret by the government, à la alleged UFO conspiracies) were simple physically, astronomically impossible.

Sorry.

Don Firth