Pisthetairos and Euelpides got "tired of their home city of Athens. Its tedious bureaucracy and incessant legal disputes were wearing the old men down and so, like many a modern day city dweller, they decided to move out of town for a more peasceful life. Leaving the city and their debts behind, they went in search of Tereus, a character from Greek myth, whom the gods had turned into a hoopoe bird. Their reasoning was that Tereus, having once been a human and now a bird, might have come across 'a nice cushy city, soft as a woollen blanket, where we could curl up'. When they found him, however, none of the bird's suggestions were quite the ticket. Cities just aren't carefree places, they realised, and whilst the life of birds is carefree, they don't live in cities. Then one of the old fellows proposed an idea to the birds. What if together they founded a city in the sky - one up in the clouds, away from earthly concerns? This new city would become all-powerful, he explained, for the birds could hold the gods to ransom: it would be up to them whether or not to let the fumes from sacrifices below pass up to Zeus and the others above. It would also be the perfect place for the two Athenians to escape to. So delighted were the birds with the old man's plan that they immediately agreed and appointed him as their leader. Eating a magical root, he was able to grow wings, which was clearly going to be a help in navigating the new city. Nevertheless, escaping to a Utopia in the clouds was not without it's difficulties. Not only did the new leader of the birds and his friend have to fend off a whole host of profiteers and tricksters, who wanted to come and live in their cloud city, they also had to contend with some rather angry Olympian gods. It all turned out well in the end, though. With a little persuasion, they managed to convince the gods to hand power to the birds, and pretty soon the old fellows ruled the roost in their dream city in the sky. Nevertheless, you might think that anyone who dreamt of doing the same was living in a Cloudcuckooland (Νεφελοκοκκυγία)  the very name that they two Athenians chose for their fantastical Utopian City"
Pretor-Pinney, Gavin. "The Cloudspotters Guide: The Science." History, and Culture of Clouds. PERIGREE (2006).