The staged-construction of Alibey Dam on the Alibey Creek near Istanbul in Turkey started in 1968 and ended in 1983 to generate a reservoir to meet up the water requirement of Istanbul. Alibey Dam had a geotechnical challenge of a 29.5 m high zoned earth-fill dam on 33-m-thick soft alluvial foundation and occasional sand bands. Alibey Dam consists of upstream cofferdam, downstream cofferdam, main body and test embankment. Before the construction of Alibey Dam, both extensive field and laboratory tests were performed to determine the engineering parameters of foundation soils. During the construction and approximately 30 years after the construction of the dam, the behavior of the foundation soils and the embankments were monitored using extensive instrumentation placed into the foundation soils and the dam body. All available performed and measured data before the construction, during the construction and approximately 30 years after the construction are collected and presented here to shed light on the staged construction of the dam on soft clay. © 2009 IOS Press.