Does someone have big plans for these buildings?

Why buy just one townhouse when you can buy two? The new owner of 153-155 East 78th Street certainly thought so. But what does he or she plan to do with two houses? Could the new owner have plans besides renovating the space into a huge single-family mansion?

The listing, held by Corcoran broker Anne Snee, helpfully suggested that the new owner might like to make the two townhouses, which are both single-family dwellings with restricted ground-floor retail, into a 25-foot-wide mansion. While such a space would no doubt be magnificent, and the home appears to be in excellent shape from the listing photos, it doesn't take a fool to see that site would also make a magnificent site for a housing development.

Located just off Lexington Avenue, the twin houses are about a block outside of the Upper East Side historic district, and together the 47-foot-tall buildings each have about 11,500-square feet of unused air rights. The listing helpfully points this out, along with the fact that the c1-8x zoning allows the ground floor to be built up to a depth of 95 feet.

We called Ms. Snee to see if she had any information about the plans of the mysterious buyer—Spruce 317 West 77th Street—who bought the buildings for $12.2 million, according to city records. The purchase price was generous considering that owners Pamela Usdan (No. 153) and Jon A. Turner (No. 155) only wanted $11.9 million.

"They're lovely buildings," said Ms. Snee, who told us that she had also sold one of the homes some 30 years before. "As for the buyer, I can't really comment on what he's going to do."

Unfortunately, the buyers were not interested in speaking with The Observer about their plans for the site. The LLC is registered to Spruce Capital Partners LLC, who have taken out $15 million and $30 million mortgages on the properties, according to city records.

Not that the owners are necessarily planning anything on the scale of the Toll Brothers tower that will level two townhouses in Carnegie Hill. They might just be looking to flip the place post-renovation. As might be expected, the LLC owned, until recently, a townhouse at 317 West 77th Street that it bought for $1.8 million in 2004. After a makeover from architect Guerin Glass, they sold the space for $11.1 million in March (a healthy profit even if they'd been trying for $13.7 million).

The question is whether an awe-worthy renovation could even net even twice the price the new owners paid, especially considering the fact that the townhouse is east of Lexington.

kvelsey@observer.com