Islamic State group fighters advanced to the gates of ancient Palmyra Thursday, raising fears the Syrian world heritage site could face destruction of the kind the jihadists have already wreaked in Iraq.

As it overran nearby villages, IS executed 26 civilians -- 10 of whom were beheaded -- for "collaborating with the regime," the Syrian Observatory for Human Rights said. 

In the past three days, Christie's in New York City has sold over $1 billion worth of art, a frenzied spectacle that showcases the world's rising class of uber-wealthy and its appetite for trophy art.

Wednesday's bidding was spirited at Christie's contemporary art auction highlighted by iconic works by Lucian Freud, Francis Bacon and others.

In an unusual move by Tehran's mayor, hundreds of copies of famous artworks — both of world masters and Iranian artists — have been plastered on some 1,500 billboards across the city, transforming the Iranian capital into a gigantic, open-air exhibition.

The 10-day project, which ends Friday, has stirred both appreciation and criticism. But whether people like it or not, the message is simple, according to Ehsun Fathipour.

U.N. and Arab officials began a two-day conference on Wednesday to seek ways to combat the "unprecedented" destruction of heritage sites by jihadist groups in the Middle East.

The Cairo conference comes amid an international outcry after the jihadist Islamic State group circulated a video last month showing its militants bulldozing the ancient Assyrian city of Nimrud in northern Iraq.

The mayor of a Japanese city that wants to register letters written by World War II kamikaze pilots as important global heritage, on Wednesday defended the plan, despite criticism it was glorifying war.

The city of Minami-Kyushu last year filed an unsuccessful application to include farewell letters written by the suicide fighters on a United Nations world memory list.

An over-the-top re imagination of 19th century American-born artist James Whistler's iconic Peacock Room is going on display in the Washington museum that is home to the original.

"Filthy Lucre" is painter Darren Waterston's take on the artist's tortured relationship with his patron, shipping tycoon Frederick Leyland, who commissioned him in 1876 to create the Peacock Room in his London home to show off his Chinese porcelain collection.

A 25.59 carat "pigeon blood" ruby sold for a world record $30.33 million at auction in Geneva Tuesday while a rare pink diamond believed to have once belonged to Napoleon's niece fetched $15.9 million, Sotheby's said.

After competitive bidding, the ruby went to an anonymous telephone bidder for 26.25 million Swiss francs (27.3 million euros), with costs.

A Mark Rothko painting sold for $46.5 million Tuesday at a Sotheby's auction in New York, an evening in which several records were set including one for a work by German artist Sigmar Polke.

The Rothko work "Untitled, (Yellow and Blue)", measuring 2.42 meters by 1.86 meters (about eight feet by 6.1 feet) and completed in 1954, had been estimated at between $40 and $60 million.

The United Nations cultural agency on Tuesday condemned "severe damage" caused to heritage sites in Yemen, such as Sanaa's old city, during intense bombing of the rebel-held capital.

"I condemn these destructions and I call on all parties to keep cultural heritage out of the conflict," said UNESCO director general Irina Bokova.

Intersex children, or those born with characteristics of both sexes, must not be subjected to "normalization" surgery without their consent, the Council of Europe said Tuesday.

The human rights organisation also urged states to stop classifying people under the male-female binary.