An unoccupied  waterfront mansion on Mercer Island’s west side, is set to go to auction this month.

Original plans for the house show that it could have been the largest residential structure ever built on the Island.

The property is a 1.66 acre hillside lot in the 4100 block of Boulevard Place off West Mercer Way.  The listing says the home has over 13,000 square feet of living space. City records however, show the amount of gross floor area (that includes the garage and a guest house) to be 16,324 s.f.

The main house sits just above 160 feet of Lake Washington shoreline and has deep water moorage for multiple watercraft.

A 150-inch flat screen retractable TV sits poolside.

The mega-house was first in the news on Mercer Island in 2008, when Boulevard Place neighbors complained of its size.

In July 2008,  the homeowners, David and Becky Sandwith,  submitted plans to build an indoor gymnasium rather than an outdoor basketball court. Plans show the total square footage of the home, if the gym was included, was to be about 25,000.

In November 2008, a slender majority of three Planning Commissioners unanimously upheld a code interpretation by the city’s former Development Services director that allows private recreation areas as part of Island homes.

The plans also included an auto court of 2,500 square feet, a 6,500-square-foot pool and several patios, walkways and balconies.

The owners later dropped the gymnasium addition.

City planners estimate the total square footage of the home, if the gym is included, to be about 25,000, the largest home ever built on the Island to date. Plans also show an auto court of 2,500 square feet, a 6,500-square-foot pool and several patios, walkways and balconies.

It is not clear that the homeowner even lived in the house.

The house was put on the market in 2009 at $32 million and has been featured in national magazines and the news concerning luxury real estate. Since the initial listing, the price was reduced to $28million.

A similar home, called the Lytle  Mansion on the northwest corner of the Island, originally listed at $40 million finally sold at auction in, 2010 for $12 million.