New Hibernia House is a Victorian warehouse located in Borough Market, adjacent to Southwark Cathedral in London. In the 1970s it was unsympathetically converted to offices, removing or hiding many of the original features. Our project entailed adding a two storey roof extension, creating a new basement level for a ground floor restaurant and restoring the interior spaces to their original state. The new extension is formed by a series of rectangular Corten volumes whose key dimensions are derived from the existing building below.