Global Tower rises above Beppu's convention centre district, offering one of the easiest panoramic views in the city. From the observation deck you can see Beppu Bay, the steep hills behind town and, on clear days, the patches of geothermal steam that mark the hot-spring districts.
It is a quick visit, but a useful one early in a Beppu stay because it helps orient the city. Sunset can be good, with the bay catching the light and the onsen steam becoming more visible as the air cools.