Complex sentence: Therefore, Magic Kingdom was built over a series of tunnels called utilidors, a portmanteau of "utility" and "corridor", allowing employees (called cast members) to move through the park out of sight from guests, maintaining the show's cast.
Split into simpler sentences: Therefore, Magic Kingdom was built over a series of tunnels called utilidors, a portmanteau of "utility" and "corridor". These tunnels allow employees (aka cast members) to move through the park out of sight from guests, maintaining the show's cast.