It feels deserted, abandoned, forgotten.

Yet also priceless.

The cavernous ex-Pfizer campus in northern Ann Arbor - acquired by the University of Michigan for $108 million in June - is filled with opportunity. People, on the other hand? Not quite yet.

U-M officials recently gave us a rare tour of the ex-Pfizer facilities - the first walk-through for members of the media since Pfizer announced in January 2007 that it would close the 2 million square feet of facilities.

The 2,100 Pfizer workers employed at the site at the time are long gone. But the atmosphere in the buildings feels like they just left.

“It is very eerie to me,” U-M Medical School Dean James Woolliscroft said.

Stroll into the main conference room in the administrative building and you’ll see a large, pristine, circular wooden table surrounded by a dozen expensive office chairs. One of the chairs is twisted perpendicular to the table - like someone had to leave abruptly.

Poetic, perhaps. Pfizer’s announcement was thoroughly abrupt. No one saw it coming - not the governor, not the city, not economic development officials, not the University of Michigan.

Which brings us to today. The site looks mostly immaculate. Hardly a speck of dust anywhere. Pfizer left virtually all the furniture - high-quality furnishings, tables, desks and chairs. Leather seats in lobby areas, and plasma TVs scattered throughout the halls.

The lab equipment? OK, that’s gone. Pfizer took the most valuable equipment and donated the rest to Ann Arbor SPARK’s Michigan Innovation Equipment Depot - a collection of expensive biotech tools distributed to local startup life sciences companies.

The ex-Pfizer buildings look brand new. Even the older facilities are far from dilapidated, which makes sense: The pharmaceutical giant invested $300 million in the renovations at the site in the few years before the closure announcement.

The sheer size of the facilities is daunting. You can easily get lost, particularly because the facilities are largely integrated. There’s even an underground tunnel connecting the portions of the campus on opposite sides of Huron Parkway.

The site’s girth - not to mention the pharmaceutical industry’s contraction and the global financial crisis - serves as a stark reminder that the facilities could have sat vacant for years.

“There’s huge areas of space that I never knew existed before,” Woolliscroft said. “It is massive. It was a city. That’s the closest thing."

Now, U-M has a chance to place its indelible imprint on the facilities, and the university is taking a decidedly methodical approach to the transition. Nothing rushed. The university expects to hire 2,000 to 3,000 workers over 10 years at the site, but the pace will be slow.

One thing’s for sure: The fortress-like feel of the Pfizer campus, characterized by the tight security and fenced exterior, will fade.

Stephen Forrest, U-M’s vice president for research, said the university would “develop a more human feel to it on the outside and from the inside. I’m sure that fence will come down.”

Contact AnnArbor.com’s Nathan Bomey at nathanbomey@annarbor.com or (734) 623-2587 or follow him on Twitter.