Updated

After much delay the United States opened its new $700 million embassy in Iraq on Monday, inaugurating the largest — and most expensive — embassy ever built.

The 104-acre compound, bigger than the Vatican and about the size of 80 football fields, boasts 21 buildings, a commissary, cinema, retail and shopping areas, restaurants, schools, a fire station, power and water treatment plants, as well as telecommunications and wastewater treatment facilities.

The compound is six times larger than the United Nations compound in New York, and two-thirds the size of the National Mall in Washington.

It has space for 1,000 employees with six apartment blocks and is 10 times larger than any other U.S. embassy.

In a ceremony Monday attended by U.S. and Iraqi officials, the U.S. Ambassador Ryan Cocker ushered in a "new era" for both Iraq and for the Iraqi-U.S. relationship, although critics have said that the embassy's fortress-like design and immense size show a fundamental disconnect between the U.S. and conditions on the ground in Iraq.

“The presence of a massive U.S. embassy — by far the largest in the world — co-located in the Green Zone with the Iraqi government is seen by Iraqis as an indication of who actually exercises power in their country,” the International Crisis Group, a European-based research group, said in 2006.

"The idea of an embassy this huge, this costly, and this isolated from events taking place outside its walls is not necessarily a cause for celebration," architectural historian Jane Loeffler wrote in Foreign Affairs in 2007.

"Traditionally, at least, embassies were designed to further interaction with the community in which they were built," she wrote. “Although the U.S. Government regularly proclaims confidence in Iraq’s democratic future, the U.S. has designed an embassy that conveys no confidence in Iraqis and little hope for their future. Instead, the U.S. has built a fortress capable of sustaining a massive, long-term presence in the face of continued violence.”

The inauguration of the $700 million embassy compound in the heart of the Green Zone came just days after a security agreement between Iraq and the United States took effect, replacing a U.N. mandate that gave legal authority to the U.S. and other foreign troops to operate in Iraq.

"I think we have seen a tremendous amount of progress, even since September. But the development of this new Iraq is going to be a very long time in the making, and we need to be engaged here," Crocker said.

Crocker's remarks were an indirect appeal for the U.S. to stay engaged diplomatically and politically in Iraq, regardless of the eventual withdrawal of the approximately 146,000 troops stationed here. The veteran diplomat has served before in the Middle East, where a lack of U.S. resolve in places like Lebanon 20 years ago opened that country to meddling from Iran and Syria.

U.S. diplomats and military officials moved into the embassy on Dec. 31 after spending almost six years housed in Saddam Hussein's Republican Palace, which they occupied when they captured Baghdad in April 2003.

The grandiose and gaudy palace, with its gold-plated bathroom fixtures, wall paintings of Scud missiles and enormous chandeliers, served as both headquarters for occupying forces and the hub for the Green Zone — the walled-off swath of central Baghdad that was formally turned over to the Iraqi government on New Year's Day.

The palace will now seat the Iraqi government and the office of Prime Minister Nouri al-Maliki, who did not attend the Monday's ceremony because he was traveling in Iran.

Iraqi President Jalal Talabani praised President George W. Bush and the new embassy.

"The building of this site would not be possible without the courageous decision by President Bush to liberate Iraq," said Talabani. "This building is not only a compound for the embassy but a symbol of the deep friendship between the two peoples of Iraq and America."

The Associated Press contributed to this report.