Worshipers attend Friday afternoon prayers in the mosque at the Diyanet Center of America in Lanham, Md. (Amanda Voisard for the Washington Post)

There were about 15 of them there at the beginning. Turkish American engineers who in the early 1990s worked at NASA’s Goddard Space Flight Center in Greenbelt and at the University of Maryland in College Park .

They lived in communities scattered throughout Prince George’s County, and as Turks and Muslims, they wanted a place nearby where they could meet and worship.

So in 1993, they joined together and purchased a 10.7 acre wooded area in Lanham from the Salvation Army for $302,000. Later they would purchase another six acres, spending nearly $1 million for the land.

On Saturday, several thousand are expected to attend the official opening of the Diyanet Center of America, which bills itself as the largest Islamic campus “in the Western Hemisphere.”

Turkey’s President Recep Tayyip Erdogan is scheduled to attend the official opening of the $110 million facility that was financed and built by his country.

The mosque on the campus at the Diyanet Center of America. (Amanda Voisard for the Washington Post)

On Wednesday, Mehmet Gormez, Turkey’s head of religious affairs, toured the facility, which includes a 20,236-square-foot mosque, a cultural center, guest homes and an underground sports complex containing a soccer field, basketball arena and a swimming pool.

“I am very excited about being here,” Gormez said, adding that the land was little more than a swamp when he first saw it. “It shows that people can come up with wonderful architecture, wonderful buildings.”

Gormez said his hope is that the facility will be used as a venue for peace, and that Muslims using the center will have a greater sense of belonging to the surrounding community and the country.

The center opens at a time of heightened fears about Muslims after attacks in Brussels and Paris by members of the Islamic State and anti-Islam rhetoric by presidential campaigns. But even before the most recent terror attacks, a mosque opening has led to protests and worse.

In November, a meeting about the proposed expansion of a mosque in Fredericksburg, Va., was interrupted by protesters calling Muslim residents terrorists and suggesting that the mosque would be a site for Syrian refugees.

While Prince George’s County officials say they are unaware of any threats made against the Diyanet Center, plans have been made to install additional security measures at the site. Anyone attending the opening must obtain security clearance.

The Diyanet Center of America campus, as viewed from atop the mosque minaret. (Amanda Voisard for the Washington Post)

Still, the presence of Turkey’s president at the official opening has the potential to cause even more unease. The country’s military campaign against Kurdish militants has come under strong criticism from the United States.

Maryland Gov. Larry Hogan, despite invitations personally delivered to his office in Annapolis, has declined to attend the opening. He has not given a reason. Other elected officials from the Washington region are expected to attend.

The mosque has been built in the style of 16th-century Ottoman architecture. Materials were shipped from Turkey, including marble that was used in four pillars that bear the weight of the central dome. The mosque has two towering minarets that will stand as a reminder of the time when Muslim leaders climbed the stairwells and voiced the call to prayer.

Craftsmen and laborers, 150 in all, came from Turkey to do the work.

The center opened unofficially in October, drawing Turks and Muslims from across the region with a host of activities aimed at bring their people together and presenting Islam in a more positive light than is often seen.

“The motivation behind this project is for the Turkish people to show its culture in a way that this culture deserves,” said Yasar Colak, president of the Diyanet Center of America.

County officials have embraced the center and commended its leadership for working with them throughout the building.

“It is a great symbol for our county,” Prince George’s County Executive Rushern L. Baker III said. “The new facility is phenomenal. They did great work.”

But the building of the center did not come without strong concerns from neighbors who were upset about the size of the project, the length of the construction and the noise it brought, and other issues that have arisen since its completion.

“There is a real drainage problem with the water coming from the center that needs to be resolved,” said Dorothy Durham, who lives behind the center. She and other neighbors say that because the land was elevated to build the campus, stormwater now flows into their back yards.

Sharif Salim, a retired Prince George’s County school principal who was hired to serve as community liaison for the Diyanet Center, said that a contractor has been hired to address and improve the drainage system.

Peggy Webster, vice-president of the Pressley Manor Neighborhood Association, where the center is located, said she too was concerned about the construction, and still has worries about the drainage issue. But Webster, who has lived in the community since 1967, said center officials have been welcoming to the neighbors, inviting them to tour the facility and listening to their concerns.

The center has served as a venue for a health symposium, workshops and other programs for nearby residents. Salim said the Duval High School swim team has been invited to use its Olympic-sized swimming pool.

Heidi Wahba, a native of Egypt, often brings her children to the mosque from her home in Clarksburg, Md.

“It allows my kids to relate more to our faith. To see a big masjid like this makes us proud,” Wahba said. “It will help us to introduce more people to Islam, and come and learn more. It definitely bothers me that people get the wrong reputation from all the media and some candidates. We want people to see the truth about this religion.”

Prince George’s County Council member Dannielle M. Glaros (D-District 3) said that while her constituents were concerned about the center during construction, many are now cautiously optimistic about what its opening might mean for the county.

“I am excited that so much investment has gone into our community,” Glaros said. “This is an opportunity for residents of Prince George’s County to engage in a faith dialogue.”

Ahmet Aydilek, who serves as secretary general for the center, said he wants to see Diyanet be of service to its neighbors.

‘This is not just a Muslim mosque,” he said. “The purpose is to serve the entire community. Ninety percent of the people who come here for prayer are not Turkish.”