A couple or three weeks ago I spotted a nicely cut piece of brown sandstone set into the pavement on the Viaduct Road and Ditchling Road junction. It was set at an odd angle to the existing paving, and had a very neatly cut 17 in one corner.
But what was it? I took a photo a couple of days later and forgot about it until this morning. Walking down the west side of the Level I spotted another one. Brown sandstone the same size, but a different number (perhaps a low 30?). Still no idea what they mean. Must be ART. Anyone any ideas?