In the 15 years since the Sept 11 attacks, the Lower Manhattan area has been transformed by public and private investment, according to a new city report.

New office towers, a mass transportation hub and new retail complexes that attract young professionals have sprung up in an area that suffered extensive damage to its infrastructure.

"As the rebuilding has progressed, the local economy has changed. The area has become much more residential as older office buildings have been converted to residential use and new towers are completed," said the report, "Transformation of Lower Manhattan's Economy", which was released on Tuesday.