Mirror Mirror explores the institutional definition of MoMA PS1 through the triangular figure of its courtyard, proposing the mutual reflection of this space and the city through a billowing roof surface and the redefinition of its perimeter wall as an urban mirror. The edges of the triangular courtyard are lifted to make its space visible as an urban figure, then used as the frame from which a shimmering surface of mirror tiles is draped. The tile pattern ranges from fully mirrored at its edges to a halo-like void at its lowest point, dissolving this collective accumulation of tiles to create space for a singular moment of contemplation at its center. A gravel mound lifts viewers above ground level for a direct view over the courtyard wall and accommodates tiered seating for events, while the surface of the concrete wall is mirrored to double both mound and roof between courtyard and street. A colonnade of wood beams at the perimeter of the triangle houses a variety of hanging elements for cooling and play, including mist, showers, buoys, and swings. Through a crowdsourced campaign each mirror tile is customized with an inscription of 140 characters, investing participants in the collective form of the billow and creating a memento through 17,000 personal mirrors sent to contributors after the closing of the pavilion. At night, spotlights turn the field of mirrors into a glittering backdrop for the Warm Up party and other MoMA PS1 events.