A tiny patch of Oakland moved a step closer to becoming a city historic district yesterday.

The city's Historic Review Commission voted unanimously to recommend to City Council the designation of Oakland Square, a move that would help protect the architectural character of the small neighborhood.

"I'm extremely pleased," said Nathan Hart, an architect who nominated the residential area for designation.

The commission, in a separate vote, also took a preliminary step toward recommending the old Buhl Planetarium building, now part of the Children's Museum of Pittsburgh, as a city historic structure.

In recommending Oakland Square, the commission found it met criteria for designation in three respects.

The houses, with sloping mansard roofs and large gables, represent a distinctive architectural type, one that served as a prototype for other homes in the East End.

The construction of houses around a park-like common area was unusual for city middle- and working-class neighborhoods. Developer Eugene O'Neill probably was inspired by residential squares in London and his native Dublin, according to the commission.

Commission staffers also determined that, while many of the houses have been altered over the years, removing original architectural features, there was "sufficient integrity to merit preservation and restoration."

Oakland Square includes the 3400-3700 blocks of Parkview Avenue and parts of Dawson Street. The core of the district consists of 67 houses built by O'Neill and builder Charles Chance from 1889 to 1896.

The first 26 houses were arranged in a horseshoe shape around a central park-like oval that overlooks Panther Hollow.

Hart and Kathy Boykowycz, a member of the Oakland Community Council, said they hope the designation, if approved by council, will discourage absentee landlords from buying and neglecting property in the neighborhood. Hart also believes the designation will add to the value of Oakland Square over the long haul.

"What it really does is it says to the next generation, this place is permanent, this is a place you can invest your money in and it's not going to be for naught," Hart said.

For the Buhl Planetarium building, the commission determined there was "reasonable cause" to believe it meets the definition of "historic structure" under the city's preservation ordinance.

The planetarium, when it was completed in 1939, was one of only a handful of planetariums in the country. During World War II, it was used to train aviators in celestial navigation.

The building closed in 1994, remaining vacant until last year, when it was incorporated into the Children's Museum, which supports the designation.