The tallest tower that never will be

The tallest tower that never will be

As the Tokyo Sky Tree grows, a look at the proposed 4km high X-Seed 4000
Got something to say? Then speak up! CNNGo is looking to reward 6 smart, lucky readers with $200 vouchers to spend on Wotif.com. Rise to the challenge, show your wit, share your tips, leave your thoughts - it’s easy, read our stories, speak your mind and our editors will pick the best readers' comments posted before 23:59:59 08/07/2010. Full details can be found here

Tokyo Sky TrainThe Tokyo Sky Tree became the tallest building in Japan on March 30, 2010.As the Tokyo Sky Tree continues its ascent to dominate the Tokyo skyline, we take a look at two other planned projects, that, alas, may never be completed.

When the 634 meter tall Tokyo Sky Tree opens in Spring 2012 it will be 301 meters taller than the iconic Tokyo Tower. Built by Tobu Railway in partnership with six Japanese television broadcasters -- a main purpose of the tower is to provide digital terrestrial TV since the present Tokyo Tower is now surrounded by skyscrapers -- it officially became Japan's tallest artificial structure on March 29, 2010. 

But that's nothing compared to the grand plans of Peter Neville, who created the X-Seed 4000 for Taisei Corporation in 1995. Four kilometers tall and six kilometers wide at its base in the sea, the mega-structure would also be able to protect its occupants from the change in air pressure as they climbed upwards. It was estimated to be able to house between 500,000 to 1 million inhabitants and be able to source energy from solar panels. 

Cities in the sky

While the X-Seed 4000 has now been denounced as "a plan to earn some recognition for the firm, and it worked" by Georges Binder, managing director of Buildings & Data, the Takenaka Corporation also has some grand design plans that are 'on hold' for the moment.

In 1989 they proposed the Sky City 1000, 1,000 meters tall and 400 meters wide that caught the attention of worldwide media. Capable of housing 35-36,000 residents as well as substantial green spaces, commercial areas and schools, it aims to help remove congestion in central Tokyo, where the population density stands at 5,751 people per square kilometer.

Whether it will ever be built remains a moot point, but one thing's for sure, Japanese architects don't lack ambition.

Robert Michael Poole is a specialist on the Japanese music and entertainment scene.

Read more about Robert Michael Poole
CNN Partner Hotels

Destination Berlin

From a casino restroom to a park in Seoul, the striking symbol of war and freedom has ended up in some strange places. November 9 is the anniversary of the fall of the Berlin Wall