The wonderful, Imperial Colosseum, from Trydar! Check his video tutorial below. It has a full circular arena, seats all aorund, corridors and stairs to reach the seats, an imperial stage, for the Emperor, and a very big portal, to let the beasts in! It is huge in its 136x136x74 blocks and I had to divide the booklets in 9 separate PDFs. The ZIP file is also heavy, with its 381 MB, but it worths the wait, believe me!