Studied in this paper is the three-dimensional structure of large-scale vortices in the reattaching zone of a separation bubble formed at the leading edge of a blunt flat plate with right-angled corners. Contours of two-point correlations of surface-pressure and velocity fluctuations and conditionally-averaged velocity-vector fields in several space-time domains revealed a loop-type structure of the large-scale vortices ; the height of the vortex core is about 0.18 xR, xR being the bubble length, from the plate surface ; the distance between legs is 0.6 xR ; the legs incline by an angle 56 to the surface. A qualitative picture of the large-scale cortices is proposed.