This paper presents the state of the art of characterisation of explosive loads of engineering structures. In recent years, high explosive devices have become the weapon of choice for the majority of terrorist attacks. Such factors as the accessibility of information on the construction of bomb devices, relative ease of manufacturing, mobility and portability, coupled with significant property damage and injuries, are responsible for significant increase in bomb attacks all over the world. In most of cases, structural damage and the glass hazard have been major contributors to death and injury for the targeted buildings. Following the events of September 11, 2001, the so-called “icon buildings” are perceived to be attractive targets for possible terrorist attacks. Research into methods for protecting civilian buildings against such bomb attacks has been initiated. Several analysis methods available to predict the loads from a high explosive blast on buildings in complex city geometries are examined. Analytical and numerical techniques are presented and the results obtained by different methods are compared. Results of the numerical simulations presented in this paper for multiple buildings in an urban environment have demonstrated the importance of accounting for adjacent structures when determining the blast loads on buildings.