The Mills is Hong Kong’s most significant private conservation initiative in recent years. The project involved demolition, alteration, addition and restoration of three former cotton mills, Mill 4, 5 and 6, and included installation of props, demolition of slabs and beams, structural strengthening and alteration. Original features, such as the painted walls and particular concrete stairways, pillars and plaster façades, were retained, while modern architectural elements such as curtain walls and skylights were added. It also incorporated installation of 10 lifts, eight escalators, 67 fire dampers, and five glass bridges connecting Mill 5 and 6, replacement of the iron windows of the façade, as well as building eight iron staircases and a giant glass block wall at the entrance hall. Merging these old and new design features involved comprehensive structural alteration of the buildings, making the project one of our challenging undertakings to date.