Flow visualization and heal transfer experiments are reported for buoyancy-driven flow in a cylindrical cavity filled with a fluid-superposed porous layer and heated from below. The experiments are conducted for 6, 15 and 25.4 mm diameter glass beads with silicon as saturating fluid. A highly complex, asymmetric, multicellular flow structure is observed in the overlying fluid layer. The flow extends to the porous region even at porous media Rayleigh number of 0(1). The heat transfer rate is a complex function of Rayleigh number, particle size and porous layer height, and may not necessarily decrease with an increase in the packed bed height.