As real estate development in Philadelphia slows, the most expensive project on the horizon is a state-of-the-art laboratory and classroom building set to replace a mid-century structure that lacks central air-conditioning.
The $520 million redevelopment of the David Rittenhouse Laboratory at 209 S. 33rd St. will raze two-thirds of the existing structure.
A seven-story, 325,000-square-foot replacement, dubbed the Penn Discovery Commons, will be built in its place.
The David Rittenhouse Laboratory has housed the math and the physics and astronomy departments since 1954. While the building has been the setting for multiple Nobel and Breakthrough Prize discoveries, university leaders now consider it outmoded.
“Those young, amazing experimenters are doing their work in this terrible, dilapidated old building that’s just not fit for purpose,” said Mark Trodden, dean of the School of Arts & Sciences, who has had an office in the building for over 17 years.
Penn has been considering replacing the existing Rittenhouse Lab building for 10 years, with the Daily Pennsylvanian first reporting on redevelopment plans in 2024. The new structure is designed by Los Angeles-based CO Architects, which is known for West Coast eds and meds designs, along with local partner Ewing Cole.
The project comes amid a challenging time in higher education, as Penn and other universities have faced funding cuts from the Trump administration. Last year, the West Philadelphia Ivy League school instituted a hiring freeze and other economies as a result.
Penn is still moving forward with a variety of major real estate projects from a new wrestling facility to a new theater addition to the Annenberg Center for Performing Arts.
But the new Penn Discovery Commons — and its more than half-billion dollar price tag — is the largest single project in the university’s pipeline and for the city in the coming years.
It eclipses the $450 million TerraPower Isotopes factory at the Bellwether District in South Philadelphia. The only larger project in Philadelphia is the Children’s Hospital of Philadelphia’s $2.5 billion new patient tower, which will be completed in 2028.
Why a new building is needed
David Rittenhouse Laboratory was built in phases, with the core constructed in 1954. It was Penn’s first new development on its main campus since the Great Depression and was seen as a sign of the university’s dedication to the city.
The original redbrick 1954 building predates central air-conditioning and is cooled by window units.
“It’s temperature control doesn’t work,” Trodden said. “The laboratories do not have the right structure or capabilities to do modern science. It’s just a very inhospitable place to work.”
Penn looked into renovating this portion of the existing building, but it rivaled the cost of new construction. So the redbrick portion with the David Rittenhouse Labs’ current main entrance on 33rd Street will be demolished.
“Many buildings built post World War II, particularly with government funding, were built relatively quickly, and they aren’t as durable,” said Mark Kocent, Penn’s university architect. “A lot of universities like us have these buildings from the 1950s and 1960s that were not well built.”
An expansion followed in 1967, which features the space-age addition that fronts much of the block of Walnut Street between 33rd and 32nd Streets. It was designed by Carroll, Grisdale & Van Alen, a renowned modernist firm that also designed the Pennsylvania State Office Building at 1400 Spring Garden St.
That over 80,000-square-foot portion of the David Rittenhouse Labs, built with cast-in-place concrete and brown brick, will remain and become part of the new Penn Discovery Commons.
The decision to keep this architecturally distinct piece of the building will save money and reduce the project’s environmental impact.
“The most sustainable building is an existing building, and so we evaluated this pretty carefully and [decided to preserve part of the existing building] both due to cost and sustainability and less time to tear everything down and rebuild,” Kocent said.
Discovery Commons’ redesign also adds natural light and replaces confusing-to-navigate hallways. It will include features like a green roof, stormwater management, and increased energy efficiency.
The new building will have 15% more research laboratory space than the current structure, and 57% more space devoted to classrooms and teaching labs.
The university plans to add space for socializing outside the classroom, with the hope of fostering the kind of spontaneous interactions that spur creativity and collaboration.
“There is this idea of scientists as the lone genius that sits in their lab or office and dreams up these wonderful ideas,” Trodden said. “Most of modern science looks nothing like that at all.”
What’s now one floor of public space will become three stories, dubbed The Nexus, which will serve as the main entrance and a connection between the research and academic sections of the new building.
Kocent, who trained under renowned Penn architecture professors Denise Scott Brown and Robert Venturi, says that encouraging socialization and unstructured interaction is in keeping with their ideas.
“Denise would often say the next Nobel Prize wasn’t necessarily going to be figured out at the lab bench; it was going to be figured out at the coffee shop at the end of the hallway,” Kocent said.
Faculty concerns about research disruption
The seven-story Vagelos Laboratory for Energy Science and Technology just to the east, which features similar environmentally conscious design, opened in 2024. It is 112,500 square feet and cost $173.5 million to build (or $1,540 a square foot).
Replacement of the Rittenhouse lab will cost $1,600 a square foot. Penn’s development team says that prices haven’t spiked dramatically — despite the current inflationary environment — because the preservation of the 1967-portion of the building is helping to manage costs.
The cost is also held down because the Penn Discovery Commons contains a lot of classroom space, which is cheaper to build.
The university plans to begin relocating the building’s tenants at the end of next year, with demolition beginning in spring 2028. Construction would take about three years, with the goal of Penn Discovery Commons being open by Sept. 1, 2031.
The Daily Pennsylvanian reported earlier this year that some faculty based out of the David Rittenhouse Laboratory worry that relocating their lab space twice in four years could “decimate research.”
Trodden says that he understands the faculty’s concerns and that the university is committed to taking care of their needs.
“Everyone is rightly anxious about how this will work in practice,” he said, “but there’s a lot of thought going into it, and a lot of care being taken about individual people’s research needs, and the needs of departments.”
