Beneath the bustling streets of Washington, DC’s National Mall, an extraordinary discovery was made: an underground cistern, hidden for over a century beneath one of the nation’s most iconic landmarks. This forgotten relic, once part of an intricate water system designed to manage the city’s stormwater, has provided a window into the history of the infrastructure beneath the park.
Discovery of the cistern beneath the National Mall
Is that a secret chamber? Last month, there was an unanticipated archeological discovery under the National Mall as part of the @smithsonian Castle Revitalization Project. While working on the utilities under Jefferson Drive, workers opened up a large brick-lined cistern. pic.twitter.com/32xYaWH3vf
— National Mall NPS (@NationalMallNPS) September 3, 2024
Construction crews working on the Smithsonian Castle‘s renovation stumbled upon a hidden cistern beneath the National Mall. This discovery, whose opening was found beneath Jefferson Drive, reignited long-standing rumors of an underground system beneath Washington, DC‘s iconic stretch of museums and memorials. The cistern, a round brick structure built in 1847 to store rainwater, has been sealed for over 120 years.
The National Park Service (NPS) revealed the cistern measures nine feet across and 30 feet deep. While the chamber was dry and empty, its smooth brick walls indicate its original purpose of collecting and containing rainwater.
Rumors of an underground system
There’ve long been rumors that a possible labyrinth of underground structures lies beneath the National Mall. Some believe secret Smithsonian archives can be found there, although this remains a myth. However, public speculation wasn’t entirely wrong, as there are very real, staff-only passageways connecting the Smithsonian Castle to other buildings, including the National Museum of Asian Art and the National Museum of African Art.
Another tunnel exists between the Smithsonian Castle and the National Museum of Natural History, which means there’s an, albeit small, network of sorts beneath the ground, there just aren’t necessarily any secrets to be uncovered there.
Regardless, these tunnels continue to add an element of mystery and intrigue to the National Mall’s infrastructure.
Smithsonian Castle Revitalization Project
The Smithsonian Castle has been closed since February 2023 for an extensive restoration project. This is the structure’s first renovation in half a century.
It was constructed in 1855, after being funded by James Smithson, an Englishman who’d ordered his estate be used to create an educational institute named after him following his death in 1929. The project will restore and replace the historic headquarters’ windows, roof and utility systems, while preserving its iconic red sandstone exterior.
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This massive undertaking has brought a significant amount of construction to one of Washington, DC’s most iconic buildings, and the discovery of the cistern during this work has added another historical element to the project. However, as the NPS wrote on X:
“Sadly, no national treasures or secret symbols were recovered. But the cistern offers a neat glimpse into the museum’s and the National Mall’s past.”