‘A focal point, not an accessory’: behind New York’s first poster museum

At Poster House, the history of the medium is explored in unprecedented depth with examples from all over the world and throughout history

‘Nazi Porsche’ valued at $20m fails to sell amid California auction confusion

Type 64 car built in 1939 is not technically a Porsche but was still expected to fetch a high price at Sotheby’s Monterey sale

Yogi Berra’s baseball bat and a $17,500 typewriter: a visit to the auction of Philip Roth’s estate

The great American novelist died last year – and a huge stash of personal effects went on sale last week. J Oliver Conroy went along