The Grand Arena of Solstice
The Grand Arena in the city of Solstice is build around the largest Astrologos Configuration, which also happens to be the site where the God-Mage attempted his assault on Heaven. Every day at dusk the Configuration spawns powerful Ravening Beasts, which immediately attempt to break out of the arena grounds and head for the Widderlands. As with any Configuration there are also specific summoning events during various conjunctions, and two full guilds of astrologers are employed full-time to examine the Configuration and predict when other Events will occur.
Since nonstop diligence, constant study, and a sizable military force must be maintained at all time, the Arena was built to allow the needful acts of putting down the Ravenings to double as major entertainment, to bring in money to offset the cost of safety. Usually the two astrologer guilds are fairly accurate about the type and power of the Ravengings to appear, though specifics are rarely available, and thus gladiators who are sufficient to deal with each threat are always on hand (without needing to keep a group any bigger or more expensive than necessary on the field). Of course the Arena includes Skywards to ensure nothing can fly away and Earthwards to prevent anything from burrowing off. And the Solstice Guard keep a few siege machines manned at all times, to deal with Ravenings if the gladiators fail their task.
In addition to making money from the Solstones dropped by any Ravenings they kill, gladiators often receive money from sponsors and patrons, and may make some sideline betting on themselves. A fair number of gladiators are also adventurers, though the most successful gladiators consider delving into the megadungeons around and below Solstice a pointless risk, and the most successful dungeon delvers consider simple arena combat unlikely to result in the truly history-changing discoveries.