The durability of limestone used in Roman Theatre and Qait Bay's Citadel considerably decreased in the marine environment in Alexandria. As is well known, the soluble salts in sea spray play a dominant role in the deterioration of stone constituents. The investigations show that the collapse of calcite structure is due to the soluble and crystalline sulphates and chlorides within the pores of stone. In addition to the salts attack, marine and industrial pollution are responsible for the disintegration of limestone in Alexandria.