National Geographic Society has chronicled scientific expeditions, explorations, archaeology, wildlife and world cultures for more than 100 years, amassing a collection of 11.5 million photos and original illustrations.

A small selection of that massive archive — 240 pieces spanning from the late 1800s to the present — will be sold at Christie’s in December at an auction expected to bring about $3 million, the first time any of the institution’s collection has been sold.

Among the items are some of National Geographic’s most indelible photographs, including that of an Afghan girl during the Soviet invasion of Afghanistan, a portrait of Admiral Robert Peary at his 1908 expedition to the North Pole, a roaring lion in South Africa and the face of a Papua New Guinea aborigine.

Paintings and illustrations include N.C. Wyeth’s historical scene of sword-fighting pirates, Charles Bittinger’s view of Earth as seen from the moon, and Charles Knight’s depictions of dinosaurs and other prehistoric animals.

They are being auctioned “to celebrate our legacy …. and to give people a chance to buy a little part of this great institution’s history,” said Maura Mulvihill, senior vice president of National Geographic’s image and video archives.

“We think of ourselves as the unsung fathers of modern photojournalism,” she added. “I don’t think people are aware of what a massive instructive archive this is.”

Proceeds from the Dec. 6 auction, just weeks before National Geographic’s 125th anniversary, will go for the promotion and preservation of the archive and “the nurturing of young photographers, artists and explorers … who are the future of the organization,” Mulvihill said.

National Geographic sponsors and funds scientific research and exploration through its official journal, National Geographic Magazine, which reaches 8.8 million people worldwide in 36 countries and in 27 languages. The society reaches millions more through its National Geographic Channel, books and other sources.

While National Geographic is known today for its photography, early magazines were filled with artwork.

Among the fine art being offered is an oil painting by Tom Lovell of Gen. Robert E. Lee’s Civil War surrender at Appomattox. It’s expected to fetch $20,000 to $30,000.

The Duel on the Beach, a painting of two pirates by the American artist N.C. Wyeth, is estimated to sell for $800,000 to $1.2 million. Another Wyeth, James Wolfe at Quebec, was commissioned to accompany a 1949 article on the general taking Quebec from the French general the Marquis de Montcalm. It has a pre-sale estimate of $30,000 to $50,000.

Steve McCurry’s photograph of the Afghan girl carries an $8,000 to $12,000 pre-sale estimate. McCurry has made a special print of the image for the sale, and part of the proceeds from it will be donated to the Afghan Girls’ Fund.

There’s also Edward Curtis’ 40-volume photo portfolio and book, The North American Indian, believed to have been owned by Alexander Graham Bell. It’s estimated at $700,000 to $900,000.

The sale also contains some images that have never been published, including a selection from Herbert Ponting, who produced some of the most enduring images of the Antarctic.