PORTLAND – The Libra Foundation, the charitable trust established by the late philanthropist Elizabeth Noyce, is putting up for sale seven properties with a total of 724,812 square feet of space and 1,000 parking spots in downtown Portland.

Among those properties is the Portland Public Market and its skybridge-connected parking garage, which was modeled after farmers markets in other cities and was designed to promote economic development in a struggling neighborhood.

Libra hopes to gross more than $65 million, which would be the most expensive downtown real estate transaction in Portland’s history, commercial brokers say.

Libra’s action, while significant, wasn’t unexpected.

In 2001, Libra sold Maine Bank & Trust to the parent company of Chittenden Bank of Vermont for $49.3 million because of federal banking regulations and the estate terms set by Noyce, who died in 1996. In 2002, Libra separately listed and sold four landmark downtown properties that fetched roughly $34 million.

The sale of its remaining downtown buildings takes advantage of a hot commercial real estate market to invest in other ventures.

“The plan was always to sell” the properties, said Owen Wells, Libra’s president. “We kept them longer than we had intended.”