Now there are several opportunities to live on America's oldest residential block (if you can shell out at least $650,000).

A third home in the past month has come on the market on Elfreth's Alley. That's nearly 10 percent of the homes on the historic cobblestone street.

The latest row home to come up for sale – just listed on July 8 – is 125 Elfreth's Alley. The 3,122-square-foot home, selling for $649,900, has four bedrooms and two-and-a-half baths. The home is divided into two units: the first and second floor owner's unit, and the upper unit, which was rented. Both spaces have two bedrooms and private entrances.

We wrote about its next door neighbor last month; the 'baker's home' at 123 Elfreth's Alley selling for $795,000. Soon after that, another home – 133-35 Elfreth's Alley – was listed for $850,000.

Realtor Adam Atacan of Keller Williams Realty said that since 1992, there's been an average of one home on the block sold every two years, but the activity has increased the past few years. In the past 18 months, three homes have been sold, and one is currently in foreclosure.

What's even rarer is that all of these homes for sale are on the north side of the street (the odd numbered houses), which Atacan said is where homeowners tend to stay longer.

"Homes on the north side of the street are larger – they're built federal style – and slightly newer, so folks tend to hold on to them more," he said.

Why the sudden rush to sell these rare homes? Bari Shor of Berkshire Hathaway HomeServices Fox & Roach says it could be for a number of reasons, but the home sales "indicates sellers see the improving market and have confidence in it."

Atacan said this is the fourth time in 20 years that there's been this many Elfreth's Alley homes for sale at the same time: four listings in 1994; three listings in 2002; and four listings in 2012. He said the reason now could be because "sellers are now noticing the market is hot and the inventory is low."

"Some people were probably holding off on the sidelines until they saw the market active again," he said. "They were probably thinking of selling and just waiting for the right timing."

123 Elfreth's Alley >

125 Elfreth's Alley >

133-35 Elfreth's Alley >

Know of an interesting property in the Philadelphia or South Jersey region? E-mail us!

Browse Philadelphia Recent Home Sales »