The Hanging Gardens of Babylon are an architectural form called the ...

Answer: Four-sided architectural design.

Explanation:

According to some sources, the Babylonian gardens had a shape that we can roughly associate with today's four-sided architectural form. The very establishment of these gardens in Babylon creates much controversy among scholars, and as a result, there are scarce and no historical sources on the existence of the gardens. Be that as it may, based on what science the Babylonian gardens have at their disposal, they are listed in the seven world wonders of the Native world.

They were built during the time of the most potent Babylonian ruler, Nebuchadnezzar, who created this architectural marvel out of love for his wife. The fusion of architecture and natural atmosphere give a unique charm to the Babylonian gardens. According to some descriptions, the gardens were a tranquillizer for the soul, and as such were listed as the largest and most beautiful botanical garden in the ancient world.