Over the years, the Atlas Obscura community has scoured the globe to bring you the most fascinating, unique, and unusual places—some in plain sight, others way off the beaten path. Last week we hit a big milestone when we added our 25,000th place to that database: The medieval ruins of Songo Mnara on an island off the coast of Tanzania. Atlas Obscura began with the Atlas itself, and this collection of wonder continues to be a central part of what we do—helping people plan trips, explore the world, and learn…