Great West Mutual Life has sold part of the former YMCA building at 1421 Arch St. to Arch Street Hotel Partners, L.P., a subsidiary of Development Services Group Inc. of Memphis, Tenn.

The $8.5 million sale, negotiated by CB Richard Ellis Inc., includes the main lobby and floors 5-10 of the two-part condominium building.

The 125,000-square foot structure is a 10-story Georgian revival style building designed by renowned Philadelphia architect Horace Trumbauer. It was built in 1911 as the YMCA.

It was last renovated in 1985 and housed the Philadelphia District Attorney's offices from 1986 until 2006. DSG said it has plans to redevelop the property into a luxury hotel for a chain that was yet to be announced. The remainder of the building will house Sweat Health Club, offices and retail space.

"We are bullish on downtown Philadelphia," said Gary Prosterman of DSG. "This is a spectacular building. The planned expansion of the Convention Center is icing on the cake," he said. "We are thrilled that we can bring this high quality European styled hotel to the city center of Philadelphia."

1421 Arch is only a half-block from the Convention Center's planned Broad Street entrance.