After standing vacant for more than a year, the downtown landmark National Hall could be set for a new round of development.

The owners of the property, Greenfield Partners, a Norwalk-based commercial real estate firm, on Thursday submitted a preliminary proposal to the Planning and Zoning Commission that calls for zoning changes to allow for development of a new office complex at National Hall.

The pre-application would precede a formal application by Greenfield for a text amendment to zoning regulations for the Historic Design District, where National Hall is located. Among a series of requested changes, Greenfield's preliminary plan asks the P&Z to eliminate a ban on office use on the ground floor of properties in the HDD.

Greenfield's new proposal represents the latest chapter in a tumultuous recent history for the iconic property, which sits on the west bank of the Saugatuck River. The P&Z approved an almost identical package of zoning changes proposed by Greenfield in December 2009. At the time, Greenfield was a prospective buyer looking to acquire the property from then-owner, Antares Investment Partners.

A pair of west bank merchants subsequently appealed the decision to the Representative Town Meeting. In January 2010, the RTM upheld the petition, which ruled out Greenfield's plans for an office facility.

Two months later, the building's then-occupant, the Inn at National Hall, closed. The boutique hotel had operated at the site since 1993. In April 2010, a Greenfield affiliate acquired the mortgage on the property and ultimately foreclosed on it. Greenfield now owns the landmark.

Greenfield Partners' pre-application also outlines redevelopment for other several west bank properties that it owns, such as the former site of the Peter Coppola Salon on Wilton Road. That space, currently vacant, could house a new restaurant. Another restaurant could open within the same complex of buildings, according to the proposal.

A call and an e-mail sent to Greenfield Partners' lawyer, William Fitzpatrick, were not returned by press time.

In addition to the demise of the inn, a series of retail store closings and vacancies have plagued the west side of the Saugatuck in downtown Westport in recent years.

New occupants of National Hall, however, could spur revitalization of the area, since the building is generally recognized by town officials and business owners as the economic anchor of the west bank. Built in 1870, the Italianate-style building housed a bank, a meeting hall, a furniture store prior to the inn's opening.