When former presidents and other prominent speakers visit Yale, their security details arrive early to conduct a thorough investigation of campus. Besides scouring classrooms, buildings and dormitories, a hidden layer of the University usually gets special attention: a sprawling network of tunnels underneath nearly all of Yale’s central campus.

“[The security officials] always want to get into the tunnels,” said Tom Downing, a senior energy engineer. “They want to see all the different access points to the tunnels and make sure they’re secure.”

More often, the subterranean labyrinth remains unoccupied and unnoticed by the thousands of Yalies trudging above as the rabbit warren of passages carries steam between buildings to regulate temperatures.

When the University’s original residential colleges, Sterling Memorial Library, the Hall of Graduate Studies and other buildings all went up during the 1930s, architects also mapped out underground tunnels for transporting electricity and steam. As a result, all the colleges are connected to each other, as well as to Payne Whitney Gymnasium, the Law School and other campus landmarks. Throughout history, the tunnels have served a relatively mundane function, but they have piqued the interest of mischievous student explorers for decades and once, in the 1950s and ’60s, served as a makeshift fallout shelter.

John Meeske ’74, associate dean for physical resources and planning, said the tunnels — which are officially off limits to students — have always evoked a certain “fascination and mystery.” He recalled rumors and stories from his own bright college years about where the passages lead and what lies inside them.

“It’s always the same idea of a place you’re not supposed to be in for security reasons,” Meeske said. “Some people want to get to the top of Harkness Tower or the ‘castle’ on top of Sterling Library. It looks romantic from a distance. There has always been a lure to these far-off places.”


The tunnel system is more than two miles long in total, and the twisting network extends around Grove Street Cemetery, up Science Hill, out York Street to the intersection with Chapel Street, down Whitney Avenue to Timothy Dwight College, and across Old Campus to College Street. The labyrinth branches out from Yale’s Central Power Plant, located next to Swing Space.

The plant, and the first tunnels, were built in 1918; in those days, the underground network was a state-of-the-art method of carrying coal-powered heat to the University’s dormitories and classrooms, said Louis Annino, director of facilities operations.

The tunnels — dark and dusty, with few landmarks to help engineers and maintenance workers keep their bearings — are big enough to accommodate maintenance workers, Downing said. Each passage is large enough for a grown person to navigate, but not always easily.

Annino said the tunnels were never intended as walkways for common use.

“If you don’t know where you’re going, it’s easy to get lost,” he said.

Meeske said the entrances into the tunnels from college basements and other parts of campus are kept locked — and sometimes even alarmed — but that does not always stop students from exploring.

It is easy enough to get into the tunnels by lifting a certain sewer cover and climbing down a ladder, said a student who has done so several times with friends, and who spoke on the condition of anonymity to avoid disciplinary action.

“It’s really warm down there, and sort of creepy,” the student said. “There are a lot of pipes and a big tunnel [under Cross Campus] that extends really far in both directions. It has an eerie feel.”

During the renovation of Calhoun College last year, the student explorer said he found a way into the college’s basement from the tunnels and got to see the nearly finished college before it was opened to students.

Meeske said the steam carried in the pipes is hot enough to burn, and adventurers could damage important electric equipment running through the passageways. He also cited the example of a Berkeley College student who got trapped in an air duct in 2001 and had to take a term away from Yale to recuperate.

The News was denied a tour of the tunnels from the Facilities Department, which cited safety concerns.


In the first few decades after their construction, the tunnels quietly transported electricity and steam between Yale’s buildings. But as fears of nuclear attack arose during the Cold War, Yale administrators began eyeing the tunnels as a potential refuge in the event of nuclear holocaust.

Tunnels were designated “fallout shelters,” with the expectation that they could keep out 99 percent of radiation, the News reported in December 1963. If used, the passages could have protected 34,000 people from a Soviet warhead dropped on New Haven. The University’s emergency plan, released that year, allotted 34,000 students, faculty, staff and New Haven residents 10 square feet of space apiece in Yale’s vast network of tunnels.

Following a government program to keep all fallout shelters well stocked, the tunnels were supplied with food, water and sanitary and medical supplies. Cans of water, once emptied, could be used as toilets.

Professor Emeritus of History Gaddis Smith, who taught at Yale during the Cold War, also recalled that biscuits and pain medications were stored in college basements, though he said the supplies were gone by the time the threat of nuclear war subsided in the early 1970s.

“The supplies were not sustained,” Smith said. “Rats got into the biscuits, the water cans rusted and drained … and for some strange reason all of the drugs were gone.”

Henry Chang ’65, for one, said he remembers such evacuation plans involving the tunnels but does not recall Yale running any practices or drills.

Still, Yale was in touch with the United States government about security initiatives throughout the mid-1960s and hired a “civil defense director,” Col. Richard Gimbel ’20, to take charge of emergency plans. The University also offered a course in radiation detection in the fall of 1963, and one in fallout shelter management in the spring of 1964, the News reported at the time.

Smith said he remembers yellow and black signs indicating “fallout shelters” installed on several Yale buildings, as well as stocks of supplies maintained in the basements of the residential colleges for more than a decade.

But he said he does not remember anyone — administrators or students — taking the emergency plans very seriously.

“It was a lunatic world during the Cold War,” he said. “I never worried about it. I don’t think students did.”


After the scare of nuclear war died down, the tunnels were again used just for their original purpose.

University Secretary Linda Lorimer said the tunnels are not part of any current emergency plan, noting that while contingency plans exist for major disasters such as a campuswide pandemic or a school shooting, none of these scenarios involves the use of the tunnels.

Today, the power plant produces steam to generate heat and chilled water for air conditioning, which run through pipes in the tunnels. The passages also carry some wiring for telecommunictaions, such as phone lines and ethernet cables, Downing said.

He said it is unusual to see a system of pipes within concrete tunnels in modern building projects; most modern construction projects — such as Yale’s West Campus — use double-enforced pipes buried directly in the ground, he said.

Assistant Dean of Yale College Jill Cutler, who oversees the Executive Committee, said that since the tunnels are kept locked, entering them is trespassing. Students caught in the tunnels are brought before the committee and could receive anything from a warning to probation, she said.

Although connecting routes between residential colleges are closed to everyone but maintenance workers, some basement facilities are still connected, such as Pierson and Davenport and Branford and Saybrook. A large tunnel also connects the two halves of Berkeley College.

There are underground passageways between many of the major libraries and museums on campus. One such tunnel connects the Yale University Art Gallery and the British Art Center. YUAG Director Jock Reynolds said the tunnel is seldom used by the museums but occasionally comes in handy for transporting art between the two.

Despite their enduring air of mystery, Annino warned that the tunnels may not be the most exciting part of campus to explore.

“It’s dark, and there’s nothing down there but wires and pipes,” he said.