In the present study, we investigate the computation of the Lagrangian second-order structure-function to characterise the multiscale dynamics of turbulence from measured particle trajectories. We performed time-resolved three-dimensional particle tracking velocimetry (4D-PTV) to study the anisotropic and inhomogeneous flow field of the wake behind a cylinder at a Reynolds number equal to 3900. We performed Lagrangian statistical analysis on nearly 12000 trajectories for 4000 time steps.