From the Super Mario Wiki
Linguine Colosseum is a large, spacious colosseum located in the Linguine Empire, which it is apparently in the center of; the Linguine Colosseum was seen in In The Super Mario Bros. Super Show! episode "The Great Gladiator Gig".
The Linguine Colosseum is extremely large, having rows upon rows of stands for spectators to events held in the colosseum to sit in. Underneath the colosseum is a large system of catacombs containing various passages and cells, this dark area is lit by several wall mounted torches. Horses and possibly other creatures are seemingly kept in these catacombs. A portion of the colosseum was seemingly destroyed accidentally by Emperor Augustus Septemberus Octoberus Koopa when he was bashed into a support pillar of the colosseum, causing a wall to collapse.
Brutius Maximus Grouchimus, a muscular gladiator, claims to be the guardian of the Linguine Colosseum, despite this though, he acted as a minion of the evil Emperor Koopa in "The Great Gladiator Gig".