It is unclear what prompted Flatley to make the decision to retreat on Braintree Hill, especially at a time when suburban office parks are becoming a darling among yield-starved investors. Prominent assets throughout Route 128 are being rushed onto the sales block to meet the demand, and Braintree Hill was considered among the top prospects available.

Several estimates had the park trading in the $120-million range. "That was the goal," acknowledges one industry professional. Flatley had retained Cushman & Wakefield to sell Braintree Hill, which has six buildings located on a 24-acre expanse offering sweeping views of Downtown Boston and the Blue Hills. Rents there are estimated by one source to run between $20 per sf and $24 per sf on a gross basis.

Officials at C&W would not comment on the status of Braintree Hill when contacted by GlobeSt.com, and Flatley did not return a phone call by press deadline. Sources insist, however, that the park is not on the market.