“The stairs!” Frank yelled. “No way this horse can pull a chariot up that many flights of—OH MY GODS!”
Thankfully the stairs were wide enough for the chariot, because Arion didn’t even slow down. He shot up the steps with the chariot rattling and groaning. Hazel glanced back a few times to make sure Frank and Percy hadn’t fallen off. Their knuckles were white on the sides of the chariot, their teeth chattering like windup Halloween skulls.

The Son of Neptune, Chapter XXXII