Structural preservation of the Temple of the Oracle in Siwa Oasis,Egypt

Abstract

The Oracle of Siwa, in the Libyan Desert, was one of the important cult sites in the classical period. For almost 1000 years the oracle was a place of pilgrimage, famous especially because of the visit of Alexander the Great in 332 BC. The temple itself was dedicated to the Egyptian god Amun and was constructed by Greek architects using alternating courses of solid binders and stretcher courses of massive limestone slabs enclosing a rubble-mortar core. Throughout its 2500-year history the temple complex was used by various groups for different purposes.

Situated near the rim of a hill the temple itself was threatened by continuous erosion of the hill slopes. During the first visit in 1993 it was decided to undertake immediate structural preservation of the critical parts of the building. In 1994 a reversible temporary reinforcement of the northern wall was applied. This was done in order to make future interventions more secure. Early during the damage assessment, the need for an extensive reinforcement of the bedrock was discussed. Before critical interventions took place the site was fully surveyed. Due to the high salt content of the anhydrite mortar and the building stone the interventions were carried out with a minimum of water. In the course of three campaigns in 1997, 1998 and 1999, the northern, the western and the opposite southern walls were reinforced by pre-stressed stainless steel anchors and secured by anchor plates. In 1999 the fissures and cracks of the bedrock were grouted with gunned concrete. The temple should be structurally stable for the next hundred years, but the problems of nonstructural decay of the walls have still to be addressed.