Columnar defects generated by heavy-ion irradiation are promising structures for pinning magnetic flux lines and enhancing critical currents in superconductors with high transition temperatures. An approach that combines chemical etching and magnetic decoration was used to highlight simultaneously the distributions of columnar defects and magnetic flux lines in Bi2Sr2CaCu2O8 superconductors. Analyses of images of the columnar defects and flux-line positions provide insight into flux-line pinning by elucidating (i) the occupancy of columnar defects by flux lines, (ii) the nature of topological defects in the flux-line lattice, and (iii) the translational and orientational order in this lattice.