Proceeding of the Joint International Symposium on Deformatuon Monitoring. 2-4 November, 2011. Hong Kong. China. Report. The paper discusses some peculiar aspects of the measurement of deformations of large structural systems like breakwaters, embankments, dams, long bridges, tunnels and lifelines. These systems, indeed, may extend for several kilometers in length. Apart from the use of conventional topographical survey, modern techniques have made available a variety of non-conventional methods that have been proven to be very useful in assessing the state of deformation of the above mentioned structural systems. In particular, GPS station networks, satellite radar imagery, long-base and distributed fiber optic sensors are described in the first part of the paper. Some examples of application of these techniques are then presented in the second part of the paper. Among these applications, the settlement monitoring of the "Duca di Galliera" breakwater in the Port of Genoa, performed from 2002 to 2005 with GPS sensors, and a few cases of deformation monitoring of dams, levees and tunnels with distributed fiber optic sensors are described in detail. Some aspects of the engineering interpretation of the data obtained from the measurements are also discussed.