MECCA, Saudi Arabia - Five times a day across the globe devout Muslims face this city in prayer, focused on a site where they believe Abraham built a temple to God. The spot is also the place Muslims are expected to visit at least once in their lives.

Now as they make the pilgrimage clothed in simple white cotton wraps, they will see something other than the stark black cube known as the Kaaba, which is literally the center of the Muslim world. They will also see Starbucks. And Cartier and Tiffany. And H&M and Topshop.

The Abraj al Bait Mall - one of the largest in Saudi Arabia, outfitted with flat-panel monitors with advertisements and announcements, neon lights, an amusement park ride, fast-food restaurants and a lingerie shop - has been built directly across from Islam's holiest site.

Not everyone considers this progress.

"Mecca is becoming like Las Vegas, and that is a disaster," said Ali al-Ahmed, director of the Institute for Gulf Affairs in Washington, a Saudi opposition research organization. "It will have a disastrous effect on Muslims because going to Mecca will have no feeling. There is no charm anymore. All you see is glass and cement."

The mall, which opened a week before the annual pilgrimage, called the hajj, in December, is the first phase in a $13 billion construction boom in Mecca that promises to change how this city, forbidden to everyone but Muslims, looks and feels.

The Abraj al Bait housing and hotel complex, a 1.5-million-square-yard development that will include a towering hotel, has begun to redraw the skyline of this ancient religious city.

When the project is completed in 2009, it will include the seventh tallest building in the world, its developers say, with a hospital, hotels and prayer halls. A public-announcement system pipes in prayers from the Grand Mosque across the way, and worshipers can join the masses simply by opening their draperies.

In nearby Jabal Omar, an entire mountain is being flattened to make way for a huge hotel and high-rise complex. And elsewhere, cranes dot the skyline with up to 130 new high-rise towers planned for the area.

"This is the end of Mecca," said Dr. Irfan Ahmed in London. He has formed the Islamic Heritage Foundation to try to preserve the Islamic history of Mecca, Medina, the second holiest city, and other important religious sites in Saudi Arabia. "Before, even in the days of the Ottomans, none of the buildings in Mecca towered higher than the Grand Mosque. Now these are much higher and more disrespectful."

"Abraj Al-Bait" complex, located directly in front of the Holy Mosque

Money is certainly one of the motivators in the building boom. Every year, up to four million people descend on this city during the pilgrimage, while a stream continues to flow through here during the year, spending an average $2,000 to $3,000 to stay, eat and shop.

Billboards along the way to Mecca remind investors of the potential earnings from owning an apartment here; some claim a 25 percent return on investment. Advertisements on Arab satellite television channels remind viewers that "you, too, can have the opportunity to enjoy this blessed view."

Muhammad al-Abboud, a real estate agent, recounts tales of Pakistani businessmen plunking down $15 million to buy several apartments at a time. Saudi princes own entire floors.

A three-bedroom apartment here runs about $3 million, Mr. Abboud said. One directly overlooking the Grand Mosque can reach $5 million.

Critics of the development complain that the result is gated communities where worshipers can separate themselves from the crowds, thereby violating the spirit of the hajj, where all stand equal before God.

"All of Mecca is a sanctuary," Mr. Abboud said. "So how could something like this not be snapped up?" But some groups say the building boom also has religious motives. They accuse the archconservative Salafi, who hold great sway in Saudi Arabia, of seeking to eliminate historic spots, fearing that these sites would become objects of worship themselves.

Dr. Ahmed of London has cataloged the destruction of more than 300 separate antiquity sites, including cemeteries and mosques. He says the house where the Prophet Muhammad lived was razed and today a dilapidated library, with its windows and doors shuttered, stands in its place.

"It is not respecting the Kaaba, not respecting the house of God or the environment of the sanctuary," Sami Angawi, a Saudi architect who wants to preserve Mecca's heritage, said of the development. "You are not supposed to even cut a tree in this city, so how could you blow up a mountain? The Islamic laws have been broken."

Progress has exacted a heavy price in Mecca. More pilgrims than ever can come here, thanks to billions spent on tunnels and infrastructure to accommodate them. But in exchange, the city's once famed night market, where pilgrims brought their wares to sell, is gone. The Meccan homes and buildings that filled the area near the mosque were demolished in the 1970s to enlarge the mosque. The neighborhoods and families who lived near the mosque and welcomed pilgrims have long since moved away.

Mecca has long been a commercial as well as a religious center, but increasingly global brands dominate here.

Mr. Angawi, the Saudi architect, has led a lonely campaign within the kingdom to bring attention to the destruction of the historic sites. Dr. Ahmed has worked to lobby Asian and Arab governments to press the Saudis to stop such demolitions. And Mr. Ahmed, in Washington, has built a database of the historic spots now destroyed. Many Muslims inside and outside Saudi Arabia have remained silent about the issues, they say, fearing the loss of financing from Saudi Arabia for religious institutions and projects.

Saudi officials say they have been painstakingly preserving the Islamic artifacts they find, and operate two small museums in Mecca. In all, they say, more than $19 billion has been spent on preserving the country's Muslim heritage. They dismiss their critics as cranks who have no following.

Developers and real estate agents, meanwhile, say the construction makes room for even more Muslims to take part in the hajj, and therefore serves the greater good.

That suggests that the changes are far from over.

"Mecca has never been changed like it has now," Mr. Angawi said. "What you see now is only 10 percent of what's to come. What is coming is much, much worse."

Hassan M. Fattah writing for The New York Times