20 Grafton Street W1

The large map-like stone plaque next to the door of the Camper & Nicholson yacht shop in Mayfair was made in 2006 by the Iceland-born but London-based artist Gudrun Sigridur Haraldsdottir, who "creates scalable, multi sensual, site-specific, public and private art pieces, installations and designs," according to her website.
The pattern is taken from the plan of the site and its history, as explained in a brass plate inset in it:

"Inspired by the street plan and the new façade's form and rhythm, the piece appears as an archaeological investigation, an erosion of the façade, carefully carving away layer after layer of history, revealing the fossil imprints and lingering shadows of a medieval orchard, the site's earliest identity.
The present sun casts a shadow of the canopy, aligning different levels and plan forms of the site's evolution through history, searching for the relationship between past and present time."

Unfortunately, the photograph fails to capture the effect of the sun's rays through the glass canopy because they were taken at dusk, but there are lots of images here.

I do like the letters of the address running down the left hand side, so distorted and buried in the surface you can barely make them out.