Since its beginning in 1977, the Simon Wiesenthal Center has become a major player on the international scene, but it now faces one of its most daunting challenges.

At risk is its Center for Human Dignity-Museum of Tolerance in the heart of Jerusalem.

For the past five years, Rabbi Marvin Hier, the Wiesenthal Center’s founder and dean, has poured his formidable energies and negotiating skills into the $200 million project as the capstone of his career.

But now the project is running into a roadblock: In a petition to the Israeli High Court of Justice, lawyers for two Muslim organizations asserted that thousands of Muslims who died during the Crusades of the 12th and 13th centuries were buried at the site where the center is being built.

They also argue that associates of the Islamic prophet Muhammad were interred at the site in the seventh century.

In response, the High Court has appointed former Chief Justice Meir Shamgar as a mediator. Shamgar has a month to find a resolution on the topic.

After the years of bureaucratic wrangling and vocal opposition from influential Jerusalemites, the road seemed finally clear last May, when a festive ceremony marked the groundbreaking on the three-acre campus. Ready were architect Frank Gehry’s plans for seven buildings, including two museums, a library, education center, performing arts theater and international conference center.

But in recent weeks, workmen excavating the site unearthed bones and partial skeletons from the old Muslim Mamilla, or Maman Allah, cemetery.

There is agreement that Muslims have been buried at the site, possibly five layers deep, for many centuries.

“Never in a million years would we have undertaken this project if the government of Israel or the Jerusalem municipality had told us that we were building atop a Muslim cemetery. We would have rejected the site out of hand,” Hier said of the project, on which $10 million has been expended so far.

In a region where religion and politics are so closely entwined, the ramifications of the dispute are bound to inflame already edgy tempers.

But Hier said he was assured by local and national authorities that there were no legal impediments to building on the site, now mainly a large open parking lot.

Also on the site is a four-level underground garage, excavated and built 30 years ago, with no protests from Muslim religious authorities, according to Hier.

Even earlier, in 1964, the highest Muslim religious council in Jerusalem ruled that the cemetery had been inactive for such a long time that it had lost its sacred character and could be used for public purposes, Hier said.

Lawyers for the Wiesenthal Center presented three possible compromises at the Supreme Court hearing: build a dignified monument to the ancient cemetery, refurbish a nearby modern Muslim cemetery or rebury the bones at another site, all at the center’s expense.

Hier, while accepting the High Court ruling, is not about to quit.

“I have absolute faith that the Center for Human Dignity will rise in Jerusalem, but only in the present location,” he said. “We’ve gone through all the required processes for more than five years, all the architectural and building plans are for this specific site, and we’ve gone too far for any changes now.”

Not only would Hier reject any other site, it is questionable if one could be found.

As a spokeswoman for the Israel Antiquities Authority told the Los Angeles Times, “There are 35,000 archaeological sites in Israel. All of Jerusalem is an archaeological site. This is a place where a lot of history happened — Jewish history, Christian, Muslim.”

She added, “Where people lived, they also died. You can say that no one can build on an archaeological site, and then you won’t have a country … no one can live here.”