Some sights, like the Grand Canyon, Eiffel Tower or Sydney Opera House, are widely recognised and admired, while others are overlooked and slowly fading into obscurity. Lonely Planet's Secret Marvels of the World is a new book that celebrates these off-the-radar places, from the most awe-inspiring to outright bonkers. Here, we take a peek at just a handful of mysterious and wondrous places our world has to offer.