Who creates the Ice Garden / The Stargazer in the Night Circus?

In Erin Morgenstern's novel The Night Circus, a competition wages between two magicians, Marco and Celia, to create the best attractions for the circus. Throughout the novel, Morgenstern describes the numerous fantastical attractions that Le Cirque Des Reves (The Circus of Dreams) contains. Some of these attractions are rides, while others are tents that contain a magical show or experience.
Marco is the one who creates the Ice Garden attraction, which is a tent that contains an interior "garden" made entirely out of ice sculptures. The magic of the tent's interior helps it to seem bigger than its actual size.
Ethan Barris, the head engineer of Le Cirque Des Reves, is the one who creates the Stargazer. The Stargazer is a roller coaster that slowly moves up toward the sky at an angle so that patrons can view the stars while riding.