"I think I know a good spot to keep the guy," said Heiji, glancing at Apollo. "But if we leave you alone in there, Apollo, you gotta promise not to wander off or talk to anyone. That area isn't heavily occupied, but you could still get yourself in trouble."

In other words, NO SIGHTSEEING. The other alternative was leaving Apollo someplace right outside a door, but then a stray vampire might happen upon him.