Photo Gallery Tomorrow's Lunch?

The Plantagon Greenhouse is a massive urban structure to grow crops and combat future food shortages in urban areas. The domes, which remain in the planning stages, are planned to reach 100 meters (328 feet) into the sky, adding new futuristic bubbles to cityscapes.

Inside the dome, boxes of plants will be moved up on its spiral slope. The crops are to be planted at the bottom of the sphere and then will gradually move higher before being harvested at the top.

The Plantagon Greenhouse is the work of a Swiss-American company of the same name. It was dreamt up by the Swedish innovator and eco-farming expert Ake Olsson two decades ago. Now Plantagon aims to have its first greenhouse built within the next three years.

The Plantagon project is one of a raft of recent projects designed to make urban environments more sustainable in the long term. For example, pictured here is a project called DragonFly. The 600-meter-high (almost 2,000-foot) vertical greenhouse is shaped like the wings of a dragonfly and was created by the Belgian designer Vincent Callebaut. It is designed to house livestock and a wide range of crops.