Abstract: The construction of a suspension bridge over the Bosphorus hasintrigued many engineers over several decades. Before 1954 proposalsmade by foreign firms for a suspension bridge over the Bosphorus werenot based on thorough investigation of the existing conditions. Sincethen the matter was tackled once more ,and an American firm-De Lew ,and Cather-was appointed by the Turkish State Highway Department toproceed with the reconnaissance site surveys and investigations. Later,detailed survey ,and investigation were carried out over the selected areaby the same firm Siteinvestigations were completed in 1958 and the Engineering Firm ofthe late D. B. Steinman was called for the design. As a technician whohas taken part in these investigations I will try to give here a concise account of the procedure followed ,and the results obtained from the pointof view of an engineering geologist.