Courtesy of the Smithsonian Institution.

With the stroke of President James K. Polk’s pen, the Smithsonian Institution officially came to be 169 years ago today. About nine months later on May 1, 1847, the president joined a mile-long parade to watch the cornerstone of the Smithsonian Institution Building (now known as the the Castle ) be laid.

But the earliest known photograph of the institution wasn’t taken for another few years, until 1850, when brothers William and Frederick Langenheim took the above image.

The photo shows the completed east and west wings, but the Great Hall was still empty and only two of the Castle’s nine towers were completed. The crane is hovering above the North tower.

“The Smithsonian has hundreds of photographs in its collections of the Castle, but none of the building under construction, which makes this image quite remarkable,” said Richard Stamm, curator of the Smithsonian Castle Collection, in a release. “The photograph is important because it verifies much of the written history we have about the odd way in which the Castle was built—the wings first and the main central section last. It greatly adds to the historical record we have.”

The building was designed by architect James Renwick in a medieval revival style to signify it is an educational institution, according to the Smithsonian.

The Langenheims took the image using a process they had developed the year prior, which they called a hyalotype (from the Greek for glass and image or impression). Hyalotypes had an exposure time of about one minute and resulted in highly detailed images. The image was one of 126 views the brothers published in 1850.

The hyalotype was donated by Tom Rall of Arlington, who collects vintage photos, daguerreotypes and glass lantern slides. It will go on display today in the Castle’s Great Hall in honor of the Smithsonian’s 169th birthday.

A close-up view. (Courtesy of the Smithsonian Institution)