  I review the status of ultrahigh-energy cosmic ray (UHECR) physics.After
introducing the main experimental results and summarizing possible
intepretations, I discuss observational and theoretical constraints on the
sources of UHECRs. I comment also briefly on the role of magnetic fields.
Combining these constraints, I argue that luminuous and numerous AGN types as
FR-I and Seyfert galaxies, or alternatively hypernovae, are the most promising
UHECR sources. Finally, I sketch few of the models presented at the conference
before concluding.
