Editor’s note: You may listen to excerpts from James Murdock’s interview with Robert Hillier and Peter Morrison by clicking the link below.

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Although the official announcement was embargoed until today, both RMJM and Hillier Architecture had difficultly keeping a lid on their big news: they’re getting hitched. To the tune of $30 million, it turns out. The papers were signed yesterday at Hillier’s office in Princeton, New Jersey, and the firm’s management, along with leaders from its new Edinburgh-based parent company, will celebrate with a champagne toast at the Whitney Museum of American Art in Manhattan this evening.

For Hillier, one of the U.S.’s five largest design firms with 350 employees, the deal represents the culmination of a two-year process initiated by chairman J. Robert Hillier, who founded the company in 1966. “We haven’t been on the block, so to speak, but we have been exploring various ways to transition the firm as I got closer to being more senior than I wanted to be,” Hillier explains. “In the last three or four months, RMJM and we discovered each other and it’s just been phenomenal—an absolute perfect fit.”

He adds that several engineering firms had also courted his company, but none proved the right match. “There’s a cultural difference engineers and architects. Architects really don’t like working for engineers and engineers really don’t like working for architects,” Hillier says.

For its part, RMJM, founded in 1956 by the Scottish architect Robert Matthew and the British architect Stirrat Johnson Marshall, wanted to partner with a firm in the U.S.—the only major market where this 750-person company lacked a direct presence. The combined firm will have more than $15 billion in construction projects under design.

“We’re increasingly operating in a more global environment where our clients are not only operating in Asia and in the Middle East and in Europe, but in America—and indeed some clients who operate in all these different continents,” observes RMJM’s CEO, Peter Morrison. “The ability to actually service clients all over the world is a really powerful offering for particularly our larger clients, I think. And this is more than just operating in a region, this is about having a significant amount of people on each continent. Our four geographical business units—Asia, the Middle East, Europe, and now the U.S.—will all have in excess of 250 people in each region and that sends a strong message.”

Morrison adds that the two firms make a good match because there is little overlap in their clients—Hillier brings expertise in healthcare while RMJM has more residential experience—but much overlap in terms of culture. “We’ve worked quite hard to understand what our clients have wanted in the last few years and I think that’s resulted in us winning some pretty cool projects. Bob has that same passion and same drive and philosophy, and really that was an important part of it for me,” Morrison says.

Going forward, Hillier will be re-branded as RMJM Hillier. While the management structure in its other key branches—Princeton, Philadelphia, Washington, D.C., and Shanghai—is already similar to that of RMJM, in that they are led by both a managing principal and a design principal, these regional design principals will now assume a higher profile in running their offices, more in line with RMJM’s management structure.