A straight line passes through 5 office blocks in the City of London, plotted to an accuracy of 10 cm

The companies using the offices that the line passes through are contacted by trained volunteers and
a dialogue initiated with and within the offices concerning the installation of a series of plaques to mark the line

The volunteers begin with public-access phone numbers, and attempt to speak to the building
managers of the offices to initiate negotiations within the company

Art is never mentioned unless there is no alternative