Tokyo looking particularly pretty today.pic.twitter.com/zGTDN4REfH
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Less trollish answer, depending on audience: Classic symmetric extinct volcano with caldera; gentle slopes. Or: Clay spun by a potter with hands barely touching just after lifting them off the wheel.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.