Mariusz Klemens founded Open Architecture Office with a clear conviction: the most consequential decisions in any project are made before a drawing exists, and a practice should be built to be present at that moment.

As Founding Partner, Mariusz brings twenty-five years of experience across architecture, urban design, landscape urbanism, feasibility strategy, and delivery. He can read a proforma, run a zoning strategy, design a building from the inside out, and carry it through construction, which makes him a steady hand when a project is still finding its parameters.

Born in Poland and trained in Chicago, he came up through firms of radically different scale: from small production offices to Gensler, to landscape urbanism at Stoss in Boston, to the design rigor of Krueck Sexton Partners, where he served as Senior Associate Principal and led award-winning work in the United States and Europe. He was Design Director and Associate Principal at Lamar Johnson Collaborative, where his residential and mixed-use work, including Triangle Square in Chicago, earned multiple AIA and IIDA awards. That range is the source of what OAO promises: corporate-scale rigor with studio agility.

Alongside his building work, Mariusz is an urban designer who asks what a project means for the block, the corridor, and the neighborhood before he asks what it looks like. His independent study and film on Chicago's Broadway corridor showed up before any client asked for it, opened conversations with developers and civic leaders, and put OAO in the room where a neighborhood's next chapter is shaped. Getting there early is central to what OAO stands for.

Mariusz sees his role as the guide, not the hero. He thinks through drawing, works from the outside in and the inside out at once, and measures a finished building by how effortless it looks. He reduces uncertainty at every stage so that clients own their decisions rather than defend someone else's vision.

Mariusz holds a Master of Architecture in Urban Design from the Harvard Graduate School of Design, where he graduated with Distinction, and a Bachelor of Architecture from the Illinois Institute of Technology. He is a registered architect, AIA, and NCARB certified. He built OAO's entity, brand, licensure, and operating infrastructure before its first client was engaged, so that every project would begin with the firm already in order.

The most expensive decisions in a project are the ones made before a drawing exists, and that is where Mariusz begins.