The sanctuary of Artemis is a huge temple, with in itís front the oldest part, an altar from the 5th century BC. Soon after 300 BC the temple construction was started, and building continued for centuries. The cults of Zeus and the Roman Imperial Family may have been conducted here also. This was concluded because the cella has been divided. In 17 AD an earth quake may have required restoration. After antiquity the site was abandoned and plundered for building materials. By the 20th century only two columns that are still standing raised their capitals above ground. Excavations took place between 1910-1914 (a crane is still on the site). Probably built in the 5th century AD a Christian chapel at far end of the temple almost touches the buildings from the old religion.
On some previous pictures is was visible how the base of each column is different. The style is very similar to what you can see, for instance, at Didyma. My gallery on that is at: http://www.pbase.com/dosseman/didyma . This is a detail of such a base decoration.