When they find it, they discover that it's not actually a city, but a solid gold statue. (screenrant.com)
Besides earning a shiny gold statue, you end up with more coins, which can be used to purchase more powerful (and varied) weapons for your lineup. (waypoint.vice.com)
Ōsama, the previously unseen king of Subcon, would see fit to erect numerous gold statues of Mario around the land as thanks for his role in driving the evil dream dictator and his gang away to another dream realm. (poisonmushroom.org)