Detroit is the largest city in the U.S. State of Michigan. It is currently the 18th largest city in the United States. The Hyperborean Cyclops Ma Gasket and her two sons have a factory there in which Leo Valdez, Piper McLean, and Jason Grace ran into in The Lost Hero.

Percy Jackson and the Olympians

The Sea of Monsters

Detroit is first mentioned when the Laistrygonian Giants who attack Percy Jackson at Meriwether College Prep pose as students visiting from the city.

The Heroes of Olympus

The Lost Hero

Festus crash-lands and Leo, Piper, and Jason fall into a closed car plant. Piper recovers from a hurt ankle while Leo is looking for Festus. Jason then goes looking for Leo, who he thinks is gone missing, leaving Piper alone. Jason is then knocked unconscious by one of the Hyperborean Cyclopes. The Cyclopes eventually capture Piper as well. Leo is able to save the two using his fire powers after being contacted by a sleeping woman in the earth, who is the real reason for his mother's death. Festus' wires are replaced and the trio gets underway just as the Cyclopes reform.

Locations (CHB)
Magical Locations: Aeolia | Camp Half-Blood | Camp Jupiter | Cave of Trophonius | C.C.'s Spa and Resort | Daedalus' Workshop | Lotus Hotel and Casino | Mount Othrys | Ogygia | Olympus | Pan's Cave | Sea of Monsters | The Labyrinth | Tartarus | Underworld | Waystation
Cities, States, and Towns: Alaska | Bar Harbor | Bologna | Chicago | Detroit | Gila Claw | Indianapolis | Jamestown | Montauk | New Mexico | New York City | Palm Springs | Quebec | San Francisco | Dalmatia | Vancouver | Venice | Westport
Other Locations: Apennine Mountains | Aunty Em's Gnome Emporium | Carlsbad Caverns | Crusty's Water Bed Palace | Empire State Building | Gateway Arch | Grand Canyon | Greece | Hoover Dam | Italy | Junkyard of the Gods | Mount Diablo | Mount Etna | Mount Saint Helens | Mount Tamalpais | Pikes Peak | Polyphemus' Island | ROFL | Rome | Triple G Ranch | U.S.A. | Waterland