I visited the Sacred Pool in Pamukkale, Turkey several years ago, and it stays in my mind as an amazing place. It was developed as a spa by the Romans, who surrounded the natural spring with ornate pillars which, following an earthquake, fell into the pool and remain there to this day. Pink-flowering oleander grows wild around the pool, trailing in the water, and vivid dragonflies dart across the surface. The water bubbles (literally!) from the ground warm and carbonated. Swimming there is a very surreal experience, like bathing in warm Perrier water under the hot Turkish sun, amongst the broken columns of an ancient civilization. There may be more dramatic places on earth, but there is something truly magical about that place that is hard to define but impossible to forget.