Castle MacFrights is the sixth floor of The Last Resort in Luigi's Mansion 3. It is accessible after capturing Amadeus Wolfgeist at The Great Stage and obtaining the sixth floor's elevator button. This floor has a medieval castle theme and prominently features suits of armor and traps such as spikes and swinging blades. Upon arriving here for the first time, Luigi nearly gets hit by a falling axe. In order to get through the Front Gate, Gooigi must walk through and pull the nearby rope to open it. After reaching the Coliseum Balcony, Luigi is discovered by the castle's ruler and namesake, King MacFrights, who taunts him with the elevator button that leads to the seventh floor.
On his way to the Coliseum, Luigi encounters Goobs with swords, Goobs with shields, tomato-throwing Oozers, Mini Hammers, and Mini Goobs. At one point, Luigi gets trapped in a dungeon cell with two spiked walls closing in on him. Gooigi must defeat the ghosts in the room and pull the rope that opens the cell door so Luigi can escape. Once he reaches the Coliseum, he is challenged to a battle by King MacFrights. He gets inside a suit of armor and rides around the arena trying to hit him with his lance. After slamming his armor enough, it breaks and he can capture the king, who drops the elevator button he was holding. With this, he can access the seventh floor, the Garden Suites.