  We report measurements of energy-dependent attosecond photoionization delays
between the two outer-most valence shells of N$_2$O and H$_2$O. The combination
of single-shot signal referencing with the use of different metal foils to
filter the attosecond pulse train enables us to extract delays from congested
spectra. Remarkably large delays up to 160 as are observed in N$_2$O, whereas
the delays in H$_2$O are all smaller than 50 as in the photon-energy range of
20-40 eV. These results are interpreted by developing a theory of molecular
photoionization delays. The long delays measured in N$_2$O are shown to reflect
the population of molecular shape resonances that trap the photoelectron for a
duration of up to $\sim$110 as. The unstructured continua of H$_2$O result in
much smaller delays at the same photon energies. Our experimental and
theoretical methods make the study of molecular attosecond photoionization
dynamics accessible.
