American artist George Segal's sculpture Rush Hour of six bronze figures marching in lockstep but alone nonetheless sits in Finsbury Square, London. Segal created this sculpture from live models, encasing them in wire mesh and plaster bandages, before cutting each cast open to free the model, rejoining the mould and casting bronze figures from the plaster versions. And it talks too!
Here it is with an extra commuter (Mr. Nag):