Mount Roraima is a two-billion-year-old island in the sky — a tabletop mountain whose sheer cliffs wall its summit off from everything below. It rises from the grasslands of the Gran Sabana at the point where Venezuela, Guyana and Brazil meet, the highest of a chain of flat-topped "tepuis" at 2,810 metres. Its sandstone is among the oldest exposed rock on Earth, and the 400-metre walls have kept the plateau isolated for millions of years — long enough to make it an evolutionary island where roughly a third of the species live nowhere else, from carnivorous sun-pitcher plants to a small black toad that curls into a ball and bounces down the rocks to escape hunting tarantulas. When Victorian explorers brought back word of this walled world, Arthur Conan Doyle turned it into "The Lost World," his 1912 novel of a plateau where prehistoric creatures survived.
The summit is a maze of black sandstone carved by wind and rain into towers and hollows, scattered with the clear quartz of the "Valley of Crystals" and amber rain-pools that trekkers call jacuzzis. Reaching it means a multi-day trek from the Pemón village of Paraitepui, crossing savanna and rivers before a single natural ledge — "the ramp" — climbs the one non-technical route to the top. You sleep in "hotels" under rock overhangs, wake inside drifting cloud, and can stand at a marker where three countries meet at once. Getting here is a real expedition: the climb is allowed only with licensed Pemón guides, runs about six days round trip, and is best in the December-to-April dry season, when the trail is firmer and the summit clearer.