Carnegie Hill, a neighborhood of the Upper East Side, is known for its good bones—much of the area lies within historic districts and is dominated by brownstones, townhouses, mansions and museums. This particular property, at 121 East 91st Street, is located on a leafy and residential block of impressive architecture. The townhouse, built at the turn of the century, is no less impressive. It’s been well-maintained from the outside and well-modernized from within. It is now on the market for $7.45 million after selling for $4.4 million back in 2003.