A broad, rifted upland area on Venus centred at +25° lat., 283° long. It is about 2800 km across, and is cut by a broad north–south valley, Devana Chasma, which extends for 4600 km southwards into the neighbouring upland of Phoebe Regio. Two huge volcanoes, Rhea Mons and Theia Mons, both over 200 km in diameter and more than 5 km high, are situated in the northern and southern half of Beta Regio, respectively; Theia, which lies on Devana Chasma, has a large caldera over 50 km across with radiating lava flows. Beta Regio showed up on the first radar maps of Venus made from Earth, and the Venera 9 craft landed on its north-eastern flank.