Items of interest:

The floors have recently been refinished.

One of the original marble fireplaces is in the basement.  As we understand it, originally fires were lit in the basement, and the heat was vented through the fireplaces on the upper floors. 

There are built-in cabinets in the corner.

As a bit of trivia only, the basement was used as a doctor's office for many years with the front room being the sitting room.

Finally, there are at least 3 options for the basement:

1. The basement can be kept as-is for use by a large family.
2. As the Fowler's originally planned, the basement can be turned into the master suite.  A full size bathroom with sauna can be put where the current bathroom, utility room, and workshop sit.  The back foyer can be turned into a nice walk-in closet.  The front room can be a nice sitting room and TV room.
3. The basement can be converted into an apartment for rental income.  The house is zoned R-2C.