An experimental investigation of the flow around smooth circular cylinders in the Reynolds number range 0.8 × 105 < Re < 2 × 105 is presented. Measured quantities include spectra, spanwise correlations and cross correlations of cylinder pressures and wake-velocity fluctuations, and low-frequency boundary-layer flow direction reversals near separation. The flow motion in the critical range is found to be characterized by intermittent, symmetric boundary-layer reattachments, occurring in cells with a well-defined spanwise structure, accompanying a significant decrease in drag coefficient and a weakening of the vortex shedding.