The Arsenal on the Charles in Watertown has enjoyed a storied existence since its founding in 1816. First a producer of weaponry for the Civil War and World Wars I and II, the property then saw a quieter life as a Harvard-owned office park.

Next year, it will move on to the next chapter of its existence as the headquarters of electronic health records company athenahealth, Inc., which will buy the 29-acre property from Harvard for $168.5 million.

Fewer than 10 miles outside of downtown Boston, the property contains 11 buildings, some of which are about 200 years old. Athenahealth headquarters have been located at the Arsenal on the Charles since 2005 and currently take up a large portion of the 760,000 square-foot property.

“The Arsenal on the Charles’ open and expansive architecture, outdoor campus feel, and proximity to Boston really fit with our culture and made it the logical place for us to expand. We are excited to deepen our roots in Massachusetts, and continue our growth as an engaged corporate citizen of Watertown,” athenahealth Chairman and CEO Jonathan Bush said in a Wednesday press release announcing the deal. “I’m particularly excited about the rich history of the arsenal.... The fact that we are able to own and in fact headquarter ourselves in the very same buildings from which that first industrial revolution rose, is truly inspiring to all of us.”

University spokesperson Kevin Galvin wrote in an emailed statement that Harvard had been reviewing its off-campus property to see how it fit with the University’s goals of supporting education and research. That review, along with conversations with athenahealth, led administrators to decide to sell the property.

“We were pleased to be able to accommodate the company’s expansion through this transaction, which is consistent with our review,” Galvin wrote.

The purchase is expected to be completed in the second quarter of 2013.

—Staff writer Samuel Y. Weinstock can be reached at sweinstock@college.harvard.edu.