The latest research from the Council on Tall Buildings and Urban Habitats (CTBUH) has designated 50 tall buildings as "never completed", meaning that "site works had begun but were completely halted and no reports indicate that construction will continue".
The report, entitled Dream Deferred: Unfinished Tall Buildings, reveals that there are six unfinished skyscrapers that would have exceeded 500 metres in height – all of which could have been included in the current rankings for the world's top ten tallest buildings.
These include Dubai's unbuilt Nakheel Tower, which was set to become the tallest skyscraper in history. Designed by Pei Partnership Architects and later adopted by Woods Bagot, construction of the building started in 2008 but never progressed beyond the foundation pilings.
This project is also one of five unfinished buildings proposed in Dubai in the last 10 years that would have exceeded 300 metres but were never completed – revealing the unpredictability of the construction industry in a city commonly understood to be one of the world's skyscraper capitals.
CTBUH has produced an infographic charting the 20 tallest unfinished buildings. It also includes Moscow's 495-metre Palace of Soviets, which was halted by the Second World War, and New York's 390-metre Metropolitan Life North Annex, which was stopped after only 31 floors had been built.
"The reasons that these designs were never fully realised are varied – some fell victim to financial obstacles, others, political pressures and cultural shifts," reads the report.
The research also reveals the 15 tall buildings with the longest construction periods in history. Coming in first is North Korea's notorious 330-metre-high Ryugyong Hotel, which has been under construction since 1987.
Two other towers have also been in progress for over 20 years – the 382-metre Plaza Rakyat in Kuala Lumpur and the 340-metre Xiamen International Centre.