CHICAGO — There is a “for sale” sign in the front yard, not that potential buyers would see it. The street is closed to nonresidents by order of the U.S. Secret Service.

The house at 5040 South Greenwood Ave., next door to the Hyde Park residence of President Barack Obama and his family, hit the market here over the weekend. And in a summer of real estate doldrums, it is causing quite a stir not simply because it is a gracious, century-old, 17-room house with elaborate stained- glass windows and a charming carriage house in the backyard.

Here is what the owners say makes it a real deal: you just could not get more impressive neighbors. They are downright stately, and come with a full-time security staff that keeps an eye out like no Neighborhood Watch in the world.

Bill and Jacky Grimshaw are the empty-nesters who are selling their 6,000-square-foot house after 36 years.

The price? Hard to know, real estate agents say, because not since Richard M. Nixon lived in a New York City apartment has the market tried to assess the value of immediate proximity to the president in a dense urban neighborhood. (The Greenwood Avenue neighbors are separated by about 20 feet, a line of thin trees and an iron fence that is more decorative than foreboding.) The Grimshaws paid $35,000 in 1973; other homes in the area have sold for $1 million to $2.5 million.

“We think there’s a premium,” said Matt Garrison, the listing agent with Coldwell Banker who does not intend to put an asking price on the house. “We don’t know what the Obama effect is.”

Garrison said he tried to scout out similar parcels of residential property, but noted there was no family living next door to the White House.

“I tried to look at 12 Downing St., but that’s all offices,” Garrison said, referring to the building next door to the British prime minister’s London residence. “Here we are looking out the kitchen window at the president’s back porch. Buyers establish the market. Stuff sells for what people are willing to pay.”

On the third floor, in a playroom, a large picture window offers a sweeping view of the red brick, Georgian-style house that Obama bought in 2005 for $1.65 million.

Looking out that window, Garrison was taken by surprise. “Obama’s roof needs some work,” he said. Well, at least now they know, he joked: “The Secret Service is probably looking at us, reading our lips.”

Still, the Grimshaws — he a professor of political science at the Illinois Institute of Technology and she a transit expert and Democratic political activist — said they have managed to have an easy, neighborly rapport with the Obamas, who shot a commercial in the Grimshaws’ living room during the campaign.

“They didn’t want to mess up their own house,” Grimshaw said in jest. “Thirty people came traipsing in asking, ‘Are these the best chairs you have to set at the table?’ I thought, ‘What a nutty lark this is.”’

The Obama children, Sasha and Malia, have been known to stick their hands through the fence to pet the Grimshaws’ boxer, Roxy.

Everyone involved in the sale agreed that prospective buyers would have to be screened for security reasons before being taken seriously, but a spokesman for the Secret Service would not comment on that process or anything related to the house.

Grimshaw, an almost-retired, 71-year-old, said he never has to lock his doors. “But I also know that there are some people who would never live under these circumstances,” he said. “I’m just hoping for a good patriot, a good family man, a good Democrat.”

But would he sell to a Republican?

“Only if push came to shove,” he said.

So far, all the shoving seems to be from the curious who want to get a peek inside the house. Already more than 7,000 people have clicked on to the broker’s Web site, http://www.5040Greenwood.com.

A visit — if one is qualified to be granted a private showing — will reveal that the house is also a fixer-upper. The Grimshaws did not tamper with its original fixtures or woodworking. The electrical switches are from 1907. The kitchen and bathrooms are worn. The third floor probably needs to be gutted.

“I didn’t lavish attention on the house,” Grimshaw admits. Mocking an outraged, imaginary potential buyer, he said, “Where’s the granite? How can people live like this!”

Grimshaw has been in poor health lately. The property, which sits on a 12,000- square-foot lot, requires too much upkeep now, he said.

Even looking back to when he bought it, Grimshaw said, “We had no means to support a place like this.”

He says they had no idea, back then, about how the larger middle- and working-class area would evolve into a premier address.

Their welcome to the area back in the 1970s? Some rough teenagers from a few blocks over broke in before they had even unpacked their boxes.

Somehow, Grimshaw said, he is pretty sure the new owners will not have to worry about things like that.