I will present the results of numerical simulations which investigate the evolution of molecular clouds and stellar clusters on galaxy and spiral arm scales. Typically molecular clouds are fairly short-lived, of order 10 Myr, and are dispersed by stellar feedback and galactic shear. Stellar clusters behave similarly to their natal clouds, i.e. more bound clusters are associated with longer lived GMCs. Molecular filaments (or spurs), as observed in our and neighbouring galaxies may be the precursors of spiral arm GMCs.