Grand Mesa in western Colorado is a vast flat-topped mountain east of Grand Junction between the Colorado and Gunnison rivers, often regarded as the world’s largest of its kind. Covering about 500 square miles and rising roughly 6,000 feet above nearby valleys, it reaches around 11,000 feet and contains more than 300 lakes, reservoirs, forests, and high alpine country. Its form was created when hard volcanic basalt, laid down in multiple lava flows millions of years ago, protected softer rock below as surrounding rivers eroded the landscape. This topographic inversion, along with the mesa’s sharp climate contrasts and scenic byway, makes it one of Colorado’s most distinctive natural landmarks.