Typical steel towers are usually subjected to wind loads. In the case of sightseeing towers with lattice steel structure core and low natural frequency of the structure, human and structure interaction could play role in the tower design. This paper analyses the response of the tower structure to the excitation caused by human movement to guarantee the acceptable levels of human comfort and safe operation of the tower. There are different adopted levels of the structure and human behaviour synchronization and its effect on the whole structure. This synchronization phenomenon should be taken into account, because people respond instinctively to oscillation of a structure at a frequency which is close to that of a man’s natural movement. This paper provides the analysis of possible mode shapes of the existing 34 meter high steel core sightseeing tower structure. The paper gives recommendations for the maximum number of people allowed on the existing structure to ensure safe operation of the tower. The dynamic performance is established through the finite element modelling of the analysed structure.