The Egyptian government has announced plans to build a new capital to the east of the present one, Cairo.
Housing Minister Mostafa Madbouly said the project would cost $45bn (£30bn) and take five to seven years to complete.
He said the aim was to ease congestion and overpopulation in Cairo over the next 40 years.
The gathering, in the Red Sea resort of Sharm el-Sheikh, has attracted pledges worth $12bn (£8bn) in aid and investment from Kuwait, Saudi Arabia and the United Arab Emirates.
Mr Madbouly said the population of greater Cairo, estimated at about 18 million, was expected to double within 40 years.
The Egyptian parliament and its government departments and ministries, as well as foreign embassies, would move to the new metropolis, he said.
"We are talking about a world capital," he added.
Developers say the new city - the name of which has not been revealed - would include almost 2,000 schools and colleges and more than 600 health care facilities.
They say the project will create more than a million jobs.
It is planned to be built over 700sq km (270 sq miles) and house about five million residents.
Planners say the proposed city's site "is situated along the corridor between Cairo and the Red Sea, providing linkages to significant shipping routes.
It will be built by Capital City Partners, a private real estate investment fund led by Emirati Mohamed Alabbar. Dubai businessman Mr Alabbar built the world's tallest building, the Burj Khalifa.
"It is a natural extension for the city of Cairo," Mr Alabbar told the BBC, saying that the new development would sit on the edge of the existing city.
"It is a wonderful opportunity to be able to design something from scratch, and to design it keeping in mind the needs of the Egyptian people and the Egyptian government."
He said that the builders would be deploying the most advanced design techniques on the project, and that the city would breed "confidence" and "pride" in Egyptians.