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The Dome is an item exclusive to the NES release of Mario is Missing!. It is the roof of the famous Saint Joseph's Oratory in Montreal. It gets stolen in the entirety by some Koopa Troopas when they invade the city, and a single Koopa Troopa carries it around. When Luigi enters the city, he holds onto the Dome by himself, then proceeds to ask the city's inhabitants about what the item is. The locals provide information about the basilica, such as how the Dome is the second-largest of its kind in the world. Eventually, Luigi takes the Dome to the church's information booth and proves that it is genuine, letting the place be opened again.