The oft-admired, usually off-limits sunken terrace flanking the King Street elevation of Roy Thomson Hall like a moat played host to Interface’s annual Client Appreciation Bash. After viewing the carpet-tile maker’s latest global collection, Look Both Ways, in the lobby, partygoers descended the outdoor spiral staircase to enjoy the rare treat of mingling in this paradoxical piece of urban landscape, deep in the heart of Toronto yet as remote as a mountain meadow.