NorthMarq Capital’s Boston office completed the $40 million refinance of the 175,000-square-foot Gateway Center in Charlestown.

In a fast closing, the transaction was structured with a long-term fixed rate. NorthMarq arranged financing for the borrower through its correspondent relationship with a life insurance company.

“The combination of a repeat borrower, property condition and excellent location were major strengths of the transaction,” John Sullivan, senior vice president of NorthMarq Boston, said in a statement. “All parties recognized the value in structuring a long-term refinance at what will surely be an attractive rate for years to come. It was a pleasure to work with both the lender and borrower to complete the deal.”