Experimental results are presented that reveal the structure of a two-dimensionalturbulent boundary layer which has been investigated by measuring the time-dependentvorticity flux at the wall, vorticity vector, strain-rate tensor and dissipation-rate tensorin the near-wall region with spatial resolution of the order of 7 Kolmogorov viscous lengthscales. Considerations of the structure function of velocity and pressure, which constitutevorticity flux and vorticity, indicated that, in the limit of vanishing distance, themaximum attainable content of these quantities which corresponds to unrestricted resolution,is determined by Taylor's microscale. They also indicated that most of the contributions tovorticity or vorticity flux come from the uncorrelated part of the two signals involved. Themeasurements allowed the computation of all components of the vorticity stretching vector,which indicates the rate of change of vorticity on a Lagrangian reference frame if viscouseffects are negligible, and several matrix invariants of the velocity gradient orstrain-rate tensor and terms appearing in the transport equations of vorticity, strain rateand their squared fluctuations. The orientation of vorticity revealed several preferentialdirections. During bursts or sweeps vorticity is inclined at 35° to the longitudinaldirection. It was also found that there is high probability of the vorticity vector aligningwith the direction of the intermediate extensive strain corresponding to the middleeigenvector of the strain-rate matrix. The results of the joint probability distributions ofthe vorticity vector orientation angles showed that these angles may be related to those ofhairpin vortex structures. All invariants considered exhibit a very strong intermittentbehaviour which is characterized by large-amplitude bursts which may be of the order of 10r.m.s. values. Small-scale motions dominated by high rates of turbulent kinetic energydissipation and high enstrophy density are of particular interest. It appears that thefluctuating strain field dominates the fluctuations of pressure more than enstrophy. Localhigh values of the invariants are also often associated with peaks in the shear stress.