The Masonic Temple of Philadelphia has always been shrouded in levels of mystery, but one of those will begin being lifted in time for the temple's 135th anniversary Sept. 26.

"I think you'll see scaffolding start to come down in the early fall," said Andrew A. Zellers-Frederick, executive director of the Masonic Library and Museum of Pennsylvania, who is overseeing the exterior restoration, expected to cost $8 million to $10 million.

The temple, on Broad Street just north of City Hall, is home of the Grand Lodge of Free and Accepted Masons of Pennsylvania.

The imposing Norman-style building, constructed between 1868 and 1873, cost a then-staggering $1.6 million. It was designed by prominent architect James H. Windrim and built of Maine granite and Massachusetts syenite - a rock also found in Egypt. It has been designated a National Historic Landmark.

The building "was meant to impress. It was meant to awe," Zellers-Frederick said. Only two other Masonic temples display such grandeur, one in London and one in Stockholm, he said.

The restoration is being done by DPK&A Architects, which also restored City Council chambers and the Union League.

"There was a lot of damage done to the building when they did the Broad Street subway [1920s], when they did the commuter tunnel on the south side [1980s], when they built the prison, the Criminal Justice Center [1990s], on the other side," said Carl Doebley, a partner at DPK&A.

"In each of those cases they dug down very deep next to the building, and the building moved, and they had to keep underpinning the foundations. So we found a lot more cracks and loose stones and things that we have to repair than you could see from the ground," Doebley said.

The restoration is largely being financed by the Masons of Pennsylvania, who own the building, said Stephen Gardner, grand master of the Grand Lodge of Pennsylvania. About 1 percent - $85,000 - came from the Pennsylvania Historical and Museum Commission.

"The Masons are sort of a very . . . nice breed of people," Gardner said. "In their wills and estates, they leave money to the Grand Lodge."

When the Grand Lodge gave the go-ahead to the restoration in August, it also decided to order a detailed architectural study.

For Doebley, the exterior restoration was the easier project. The second one, a "historic structures report," includes a complete study of the history of the building and a plan for preserving it.

The interior, which took 35 years to complete, contains seven huge lodge halls, or meeting rooms, each with a distinct architectural style from some part of the world.

The Egyptian Hall has been called the only perfect specimen of Egyptian architecture in America. The room's designs and symbols are so precise that scholars study them.

Once the exterior is done, "each room will be addressed," Zellers-Frederick said. The Renaissance Hall, a favorite wedding rental site, is likely to be the first, though Zellers-Frederick offered this warning:

"There is too much to see in this room, so it is to be feared it is not the bride who will get the most attention."

The temple was also a very modern building for its time, with elevators, electricity, and a climate-control system.

While the building is being fixed, restoring membership is another challenge. Statewide Masonic membership peaked at 258,000 in 1960. In 1984, when it had fallen to 202,000, the grand lodge launched Project Solomon II, its first "awareness" campaign, since Masons do not recruit.

Despite the effort, membership is about 115,000, with the average member in his mid-60s, said Gardner, 56.

"Every Masonic grand lodge in the U.S. has a problem with declining membership," he said. "In Pennsylvania, the highest percentage of our members came in the era right after World War II, so those brothers are now 80 and 90 years old."

But there's good news, Gardner said. The average age of new members is 38. "Maybe it's the movie National Treasure that's helping to create some awareness about the Masonic fraternity," he said.

Freemasonry is first about "fellowship, fraternalism," Gardner said. "When you go into a lodge room, it doesn't matter if you're a president of a bank or the average worker. . . . Your status in society stays outside. Everybody treats each other as peers, and any of those VIP titles just disappear."

Masons also do significant charitable work. For instance, the Shrine Masons operate the Shriners Hospital for Children on North Broad Street, where care is free.

At lodge meetings, nearly anything can be discussed except politics and religion.

"Discussing politics is only dangerous," possibly hurting the relationship of two people who could be good friends, Gardner said.

To be a Mason, he said, "you must acknowledge the existence of a supreme being. In that sense we're religious, but we don't discuss religion."

Another thing they don't discuss are Masonic rituals, which Gardner said were based on the Bible, but "not really religious lessons."

Asked to explain more, he replied, "I would prefer not to go into that, per se."

Contact staff writer Ákos Beöthy at 215-854-5649 or abeothy@phillynews.com.