Adaptive reuse and extension of an existing commercial building near Ludgate Circus, in the City of London, designed by Gensler for Helical. The site sits within the St Paul’s Heights grid and the existing building breaches this in several places. The building also lies adjacent to three conservation areas (Fleet Street, St Paul’s Cathedral, and Whitefriars) and a number of listed buildings. The scheme includes the simplification of the building’s internal layout, a repositioned office entrance, new retail uses, a full facade replacement to three elevations, and reordered massing and roof extensions at the northern end of the site. The scheme also provides new roof terraces for office users and public realm enhancements, including upgraded hardscaping, improved lighting and urban greening. Our assessment included an analysis of the loss of some of the existing breaches to the Heights grid and the introduction of smaller scale breaches that were necessary to create a more unified roofscape.