The foreclosure crisis may seem like a modern problem, but its effects are being felt even by the city's historic properties.

At the end of Elfreth's Alley - believed to be the nation's oldest residential street - No. 109 stands seemingly abandoned. Built around 1811, its former owners started a restoration project, never finished it, then left it to fall into foreclosure, according to the Preservation Alliance for Greater Philadelphia. The Old City home has taken on water, mold flourishes inside and neighbors are concerned.

"We wanted to highlight foreclosure as a citywide problem," said Ben Leech, the alliance's director of advocacy. "When properties are foreclosed, historic or not, there tends to be a rapid dereliction process that is detrimental to everyone."

The house is included on an annual list that the alliance is releasing today of endangered properties. The nonprofit advocates for historic preservation and aims to feature buildings that are threatened by neglect or redevelopment.

The 2010 list has three new properties. Besides the Elfreth's Alley home, they are the Henry Pierce House, in Glen Mills, Delaware County, and Laverock Hill Estate, in Cheltenham, Montgomery County. The seven other properties have appeared on previous lists. It is the first time that the alliance has included previously listed buildings.

One of the repeats is the Divine Lorraine, the 10-story architectural landmark at Broad Street and Fairmount Avenue. The former hotel, which was on the alliance's 2009 list, has been bought and sold by various developers since 2000.

The building has been the site of numerous small fires and is overrun with squatters and trespassers, Leech said.

"It's one accident away from being lost," he said. "It's a property people are used to seeing in its current state, so it blinds us to its condition."

The building's owners have applied to the state for low-income-housing tax credits. If their application is accepted sometime next year, the city has agreed to put another $3 million toward rehabilitating it.

Also reappearing on this year's endangered-property roster is the Cruiser Olympia, the last surviving warship of the Spanish-American War of 1898. It floats off Penn's Landing near the Independence Seaport Museum.

Last month, the museum said it had found funding for interim repairs to the ship, allowing it to stay open to the public. But the Olympia's final fate is still being debated. The historic vessel, also originally featured on the 2009 list, could be torn apart for salvage or used to form an artificial reef.

The other Philadelphia properties on the list are the Alfred E. Burk Mansion, on Broad Street near Jefferson; Provident Mutual Life Insurance Building, 46th and Market streets; Dilworth House, 6th Street near Locust; Germantown Town Hall, Germantown Avenue near Haines Street, and Lynnewood Hall, in Elkins Park, Montgomery County.