These vigorous horses are racing in the palio di Siena, the famous races round the Piazza del Campo in that city. They were made in 1999 by Guy Portelli, who despite the name comes from Kent.
The subject was suggested by the name of the block of flats they were designed for, though in proper British fashion it is spelt Sienna. Naturally, the Italians can't be trusted to spell their own cities correctly (Firenze indeed. Roma? Pshaw!).
Portelli's most recent claim to fame is appearing on BBC TV's inexplicably popular Dragon's Den to raise funding for a series of works called Pop Icon (Grace Jones, Amy Winehouse etc). He showed a remarkable business acumen and flair for negotiation as you can see here.