Riaz is confident that the project will generate around 2.5 million jobs and promote investment opportunities for different industries.
Riaz signed the USD 45 billion deal on Friday with the Abu Dhabi group which also successfully runs the Al-Falah bank chain in Pakistan.
According to the agreement, USD 45 billion would be invested on different construction projects in Pakistan.
Out of the total amount, about USD 35 billion worth of investments will be made in Sindh while USD 10 billion will be invested in Islamabad and Lahore, media reports said.
"We have selected the site for our mega project which will be spread over 16,000 acres of land and also house 125,000 houses," Riaz said on Saturday.
"Besides the world's tallest building the project will include a media city, a sports city, an international complex, a medical and educational complex, restaurants, shopping centres, multiplex halls," Riaz said.
Though Riaz did not name the site where the project would be constructed but sources aware of the developments told sources that the site for the project would most likely be an island some 3 to 4 kilometres off the coast of Karachi and into the Arabian sea.
"It is most likely going to be the 'Kutta Island' which gets its name because stray dogs which are killed are dumped on it," a source said.
The source said the island was also given to another big construction magnate Emmar properties of the UAE but the project was scrapped.
Riaz said the Emmar project was scrapped and they lost millions of dollars because of the global recession and because there was no direct and strong local presence in the
Riaz rose to prominence with his 'Bahria' town residential projects throughout Pakistan and also after the Supreme Court took up the hearing of the case in which the son of Chief Justice Iftikhar Chaudhry was accused of taking money and favours from him allegedly in return of settling cases.
Riaz said the tallest building in Karachi would beat the Burj Khalifa of Dubai.
"This construction project will bring in staggering investment into Pakistan and it will benefit industries and people. My dream is to create a new Pakistan and new Karachi," he said.