Now and then, we are reminded as to why these signs are still needed in galleries around the world.

Art lovers in Miami looked on in horror on Thursday night

when a collector accidentally knocked a $42,000 (£34,870) sculpture by US pop artist Jeff Koons to the ground.

She had tapped it with her finger, witnesses at the event said.

The statue - one of Koons' iconic Dog Balloons - smashed into tiny shards, and had to be swept into dustpans by gallery staff

The accident happened during the exclusive VIP-only opening night of Art Wynwood