4th century BC is the most important period of the temple. At the times of the satraps named Mausolos (377 - 352 BC) and Idrieus (351 - 344 BC), this place gained a new appearance. In 355, during the sacrifice festival in Labranda, Mausolos escaped from an assassination towards him at the last moment. Buildings such as a series of artificial terraces here, one or two entrance buildings, a small Dor building (probably a fountain building), monumental stairs, two large feast halls (androns), shed building (named as oikoi), Stoa and Zeus Temple surrounded with columns must be constructed after this event. With the death of Idrieus in 344, such works have been stopped. Because of the big fire disaster that took place in 4th century BC, the holy area has lost its feature of being a cult place.
The excavation works here have been started in 1948 by A.W.Persson and are continuing with intervals since that time. The current excavations are being executed by P. Hellström.
The access from Mylasa to the holy area had been provided via the holy road having a width of 8 m. The laying traces on this road can be seen even today. Access to the area had been provided with one of the two entrance buildings (propylon). These were impressive passage doors made of Milas marble, having two columns and Ionian frontons on each side.
The building called as "Dor building" was located at just east of the southern propylon building with its irregular formation close to a rectangle. It is a building that is turned towards north, has four columns, a front courtyard, a marble side and is in Dor style. It absolutely had the function of a fountain building. This small building has been included in the bath complex.
200 m west of the holy building, lies the stadium whose back side is reinforced with a retaining wall. The starting and end stones of the competitions are still existing at both ends. It is supposed that some competitions have been made here during the feast of 5 days made in the holy area.