CHAPEL HILL - Hillsborough Street resident Philip Benfey had read about a group of residents who in the 1970s floated helium balloons 90 feet in the air to demonstrate the proposed height of what later became the Bank of America Center on Franklin Street.

The demonstration succeeded. By the time it was built, the building was half as high.

Citing a threat to property values in the historic district along Hillsborough and Rosemary streets, Benfey now wants the owners of the old Northampton Terrace apartments to float balloons to show how high their proposed five-story condominium towers would be if built in place of a pair of two-story buildings there now. (A third building would stay.)

Town Council members who heard developer Joe Patterson's plan Wednesday night liked Benfey's idea. Council member Jim Ward recommended floating the balloons this winter, after the leaves have fallen, so neighbors can get a clear view.

"I look forward to seeing those balloons from a number of vantage points," Ward said.

Mayor Kevin Foy, stressing again that the council could not consider the Northampton project independently from Ram Development's 332-unit Grove Park condo project next door, said he'd like to see balloons showing the heights of buildings on both properties at the same time. In all, the two developers are proposing 10 new buildings, half of them five or six stories tall.

Like Ram's representatives, Patterson, with partner David Morris, emphasized that his project, dubbed MLK-B, would attract people who want to get around on their feet, bikes or buses rather than by car.

But about a dozen neighbors who attended Wednesday's meeting were concerned that the MLK-B towers will dwarf their single-family homes on nearby Hillsborough Street.

"These will be like monsters next to these little houses," said Faye Kalman of 414 Hillsborough St.

Patterson disputed that claim, saying the slope of the property away from Hillsborough Street would make his building's foundation much lower than the homes on Hillsborough.

"The roof lines [on Hillsborough Street] will actually be higher than the roofs of our buildings," he said.

Benfey, though, would like to see what the balloons have to say.

Get $150+ in coupons in every Sunday N&O. Click here for convenient home delivery.