The 10-year pact follows an extensive search in Boston toreplace HNTB's operations at 75 State St. in the FinancialDistrict. "It's a nice property," GVA Williams principal JohnHennessey says of 31 St. James Ave. Hennessey and GVA Williamscolleague Peter Bean conducted the search on HNTB's behalf andrepresented the firm in negotiations with Capital Properties. TimLyne and Peter Conlin of CB Richard Ellis/New England acted onbehalf of the landlord. The tenant is expected to relocate nextmonth.

HNTB's deal follows a significant sublease earlier this yearwhen Sun Life Retirement Services took 71,000 sf at the 31 St.James Ave. space rented to First Marblehead Corp. Sun Life is alsorelocating from the Financial District, joining a parade ofcompanies migrating from the traditional CBD to Boston's Back Bay.The list includes several prominent law firms, but companies fromother sectors as well. HNTB is an international leader inarchitecture and transportation infrastructure planning.

The trend westward to the Back Bay has pushed average askingrates ahead of the Financial District, especially for high-endspace. According to the GVA Williams overview, class A towers inthe Back Bay have an average asking rent of $74.77 per sf versus$68.83 per sf in the Financial District. The average asking rentfor Boston overall is $52.16, says GVA Williams, which calls theBack Bay the tightest and most expensive in Boston. The directvacancy rate is just 8%, according to the GVA Williams review.