Current answer to that question: nobody will.
This is, mind you, the USA's Gilded Age answer to "summer cottage,"
which means it is located away from New York City or Washington D.C.,
intended for the denizens of same on their summer vacations,
and it looks like anything but a cottage!
I was so shocked (me from the Great Lakes region)
the first time I found out what these "cottages" really were --
they are for the one-per-cent, of course, and they are monstrous,
huge things.
Someone has well described these homes as "private hotels",
complete with their own greenhouses and carriage barns.

This particular cottage is not far from the Tanglewood summer home of the Boston Symphony Orchestra in southwestern Massachusetts, in the Berkshire range of Appalachian mountains.
It was named Elm Court for elm trees which have since died.
The Vanderbilt descendants sold this property generations ago.

It's on the market now, all eighty-nine acres of it.
And one of the things the brokers and agents and sellers always say,
is that the League of Nations and the Treaty of Versailles
were approached here with preliminary talks,
either in the house, or on the stone porch around the house, or something.

So I thought I ought to look this up. Here's what I found.
A grandchild of Cornelius Vanderbilt bought this land and built this stately home.
Their children spent their summers there.
The father of the children (not a Vanderbilt) died,
and left this Vanderbilt granddaughter a widow -- a wealthy one.

Her social connections included the recently widowed Henry White
who had been US Ambassador back in the time of Presidents McKinley and Theodore Roosevelt.
So that was the Vanderbilt granddaughter's second marriage.
And it was retired Ambassador Henry White, during the Woodrow Wilson administration,
who brought I-know-not-whom to his "summer home" for informal talks in 1919. Thus, the selling point of Elm Court.

Henry White, who was by then a senior citizen, was very much in favor of the League of Nations and the Treaty of Versailles,
but he was up against Woodrow Wilson and Henry Cabot Lodge (US Senator), who were rather entirely opposed to both --
and so the United States was part of neither.

Nobody will buy Elm Court because it is just too much.
Thirty-three bedrooms in the manor, if I read right;
forty-six bedrooms if you count the outlying buildings for caretakers and service staff.

The property has changed hands, since the Vanderbilt descendants sold it,
to firms and businesses who wanted the property for the hospitality industry.
Two things always get in the way.
One, the cost of renovations --
the house stood empty for decades and was the repeated target of vandals,
and the recent renovations were never completed, although it's better than it was.
Two, the neighbors.
The street/road is a residential one, lined with private homes,
and the neighbors want it to stay that way.

So there it sits.