I Have Heard Of And Seen Roof Top Gardens,

but this is an article about roof top farming here in Thailand,

it is the idea of Patsakorn Thaveeuchukorn, on a hotel rooftop in Bangkok, dozens of barrels of green liquid bubble under the sun the latest innovation in urban farming, proponents of the edible algae, known as spirulina, say it could help provide a sustainable source of protein as an alternative to meat, three times a week, 

Patsakorn Thaveeuchukorn harvests green algae in the barrels. “If you compare it to meat, it will take six months to grow a kilogramme of beef, but this we can grow in a week,” said Patsakorn, 

it has been described by health food experts as a super food, and it is becoming more popular worldwide, the empty spaces on top of Bangkok’s many skyscrapers provide suitable growing conditions for spirulina, because the constant high temperatures and sunlight are ideal breeding conditions, the algae also helps combat carbon dioxide levels through photosynthesis, its champions say, and growing it in cities means it can reach consumers the same day it is harvested, what a great way to use potentially unwanted space on the top of hotels and office buildings, great though it is I still think I will stick to beef as a meat, but some of the claims for spirulina as a health additive might be worth taking a closer look at.