How can we marry cutting-edge life science research to a city’s heritage of industrial innovation?

A forgotten and neglected block in Philadelphia’s Center City provided the foundation for 2300 Market, a singular new building that spans a century. 2300 Market embraces adaptive reuse by pairing a contemporary overbuild with the rehabilitation of an existing brick building and the reconstruction of an adjoining building’s terracotta facade.

When Breakthrough Properties acquired the site, it included two turn-of-the-century structures in various stages of decay. Guided by a commitment to sustainability, the developer embraced a carbon-saving adaptive reuse strategy rather than demolishing them.

The two buildings were originally designed as early 20th century showrooms for the Autocar and Locomobile companies. Their success was short-lived, and over time, the buildings served many purposes before eventually becoming vacant. Working closely with the client, contractor, and local stakeholders, the design team developed a plan that would transform these buildings into a modern hub for life science research.

Adapting these structures—built with very different needs in mind—to the highly specific demands of life sciences labs required strategic interventions. This included careful planning around lab bench spacing, building systems, and performance. While retaining their historic exteriors, the historic buildings’ interiors were completely reworked to create unified floors throughout, seamlessly integrating the patchwork of spaces, both historic and modern.

A recessed connector—or “gasket”—was introduced between the existing buildings and the new overbuild. This created exterior terraces and a clear visual break between the historic base and the modern glass structure above. The subtle shaping of the upper floors emphasizes views and gives the new volume a sense of lightness.

A singular united curtainwall system was developed and adapted to each part of the building. It includes a mix of clear low-iron glass, shadowboxes, shadowboxes, and formed metal panels to respond to light, views, and privacy needs. At the most public corner—Market and 23rd Street—the facade is most transparent, opening the building to the street. On the west, where fire codes limit openings, a higher degree of opacity was achieved without requiring alternate systems or materials.

Preserving and renewing a terracotta facade

The historic Locomobile building was not legally protected, but the team and local stakeholders opted to retain its heritage.

Preserving and renewing a terracotta facade

Although the historic Locomobile showroom and warehouse lacked formal legal protection, the project team chose to salvage and reuse its handmade terracotta facade. This decision extended the project’s broader commitment to place—honoring the site’s context and history—while also yielding embodied carbon savings by preserving and reusing existing material rather than replacing it entirely with new construction.

From the beginning stages of the project, together with the Owner and Construction Manager, KT and our consultants evaluated the existing buildings and engaged with with the City, Center City Residents Association (CCRA), and Preservation Alliance, leading to the eventual hybrid restoration and reconstruction strategy for the historic terracotta facade.

The project’s embrace of adaptive reuse and rehabilitation along with a collaborative and rigorous civic engagement process act as a model for developers, design teams, and local stakeholders to work together to transform historic structures into civic and economic assets for the future.

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A defining feature of the new building is its sculptural vertical metal panels. These fluted, asymmetrical elements create depth and shadow while reinforcing the vertical rhythm of the facade.

The system was carefully calibrated to a structural grid based on an 11-foot lab module, ideal for life sciences. The proportions of the design even reference the golden ratio, connecting modern needs to timeless principles.

The corner brick building’s masonry was carefully repaired and windowsills were restored to their original height to better connect the enhanced streetscape to the activities within the building. The second historic building was not legally protected, but the team opted to salvage its handmade terracotta facade, originally designed by local firm Ballinger and Perrot. While Breakthrough Properties develops research facilities nationwide, they challenged KT to design a building unique to Philadelphia, that is authentically Philadelphian.

The restored facade also features a new entrance at its center, marked by a custom cantilevered marquee and storefront.

In addition to quality light and views, the building provides its neighbors with a welcoming open lobby and public café. For tenants, the building offers ample space for collaboration, a gym, and indoor bicycle parking.

2300 Market brings new life to this corner of the city. What was once an underused site is now a vibrant, civic-minded destination that celebrates Philadelphia’s past while supporting its future in science and innovation.