The US Government's Defense Advanced Research Projects Agency (DARPA) has asked the public to help them find an underground facility "able to host research & experimentation" by Friday .

"Attention, city dwellers! We're interested in identifying university-owned or commercially managed underground urban tunnels & facilities able to host research & experimentation," the agency tweeted on Wednesday.

"The ideal space would be a human-made underground environment spanning several city blocks w/ complex layout & multiple stories, including atriums, tunnels & stairwells. Spaces that are currently closed off from pedestrians or can be temporarily used for testing are of

interest."

The ideal space would be a human-made underground environment spanning several city blocks w/ complex layout & multiple stories, including atriums, tunnels & stairwells. Spaces

that are currently closed off from pedestrians or can be temporarily used for testing are of

interest. pic.twitter.com/GkWKm2w2p9 — DARPA (@DARPA) August 28, 2019

According to the Request for Information (RFI), "The subterranean domain – whether human-made tunnels, urban underground infrastructure, or natural cave networks – is becoming increasingly relevant for global security and disaster-related search and rescue missions."

"DARPA is interested in understanding the state-of-the-art in innovative technologies that may enable future solutions to rapidly map, navigate, and search unknown complex subterranean environments to locate objects of interest."

As The Verge notes, the project is "likely related to the SubT Challenge, which is aimed at helping soldiers and first responders navigate these spaces more quickly. (DARPA is a military research agency, but while it often focuses on combat technologies, that’s not the sum of its work — it famously helped create the internet with ARPANET, for instance.).

The agency ran one SubT experiment in April at the Edgar Experimental Mine in Colorado, then another at two mines in Pittsburgh, Pennsylvania this month. But it’s noted that urban locations present their own challenges. -The Verge

The call by DARPA, which develops emerging technologies for use by the military, has people scratching their heads considering the agency's well-known close ties with public universities as well as companies such as SAIC, all of which have extensive facilities one would think might fit the bill.

Anyone else curious why DARPA needs a huge underground facility by Friday? https://t.co/3pdeubwI8h — Michael Coudrey (@MichaelCoudrey) August 29, 2019

what the fuck are you planning — atomicthumbs (@atomicthumbs) August 28, 2019

The agency even had a sense of humor when one Twitter user asked if they're "looking for new places to keep all the Demogorgons," a reference to Netflix's Stranger Things.

Please. Demogorgons are such a Department of Energy thing. — DARPA (@DARPA) August 28, 2019

If you want to know more about what DARPA has developed - including Robot spies, self-guiding bullets and soft exoskeletons, click here.