Featuring communist bunkers, burning gas craters and at least one sponge-rock fluorescent grotto built by Polish monks, this book reveals weird and wonderful sights that the crowds don't reach. From eerie natural wonders to historical oddities and bizarre architecture, this is a travel companion for the incurably curious. This packed and fascinating title takes its readers on a journey through the world's lesser known marvels. Dive into an underworld of the planet's most surprising, fun, perplexing, kitsch and downright bizarre sights - and explore human stories and mysterious happenings that you won't find inside a regular guidebook.