A bright grotto–a contemporary abstraction of nature–to refresh shoppers amidst delicate garments and dazzling commodities, is our design concept for this underground toilet. Situated in the CBD of Guangzhou, the TaiKoo Hui shopping mall receives tens of thousands of visitors daily, and its amenity facilities require an upgrade. The toilet aims to raise the environmental awareness in the public realm and to become the role model of sustainability in the retail sector. Sustainability, spatial sculpting and human comfort drive the whole design. White and ‘cyclorama’ setting is applied to give a bright and clean ambient – walls join the ceiling seamlessly and smoothly with curved surfaces, to diffuse light for plants to duo-function as general lighting. The toilet applies a variety of sustainable materials and equipment, including terrazzo flooring, GRG enclosure, an integrated water tap/hand dryer product etc. The baby care rooms are also upgraded with improved facilities and a playful design. The original layout is given minimum alteration to allow for a seating area and an additional baby room, the resulted kinked passage and simplified arches continue the ‘grotto’ idea.