Caryatid are korai used in an architectural setting as posts. There was a city called caryae , in the territory of sparta, that turned to be a traitor and fought as. This is why they are called caryatids because they are slaves by carrying the roof forever. Another thought is helen, the woman who launched a thousand ships. Helen was a patron to these women so they aren"t slaves. Another possibility is that they are made to represent attendance of the goddess artemis. This follows the idea that all korai are artemis. In other near eastern cultures it was not unusual to use female in furniture such as the legs of a table. Perirrhanterion, isthmia, 7th bc: washing vessel outside the temple, water was cleaned everyday, cleans/purify yourself before entering the temple, one of the earliest items that we have for women acting as support. They stand like korai but they have ram"s heads.