Westerlund 1 (Wd 1) is best known for being the most massive stellar cluster in the Galaxy, har-bouring the richest population (≥24) of stars in the Wolf-Rayet phase. The dissipated power inthe form of kinetic energy in stellar winds and expanding supernova (SN) shells has been esti-mated to reachL≈3×1039erg s−1. A fraction of the kinetic energy is available to accelerateparticles to very-high energies, e.g. at the boundaries of wind-blown bubbles, in colliding windzones in binary systems, or in the framework of collective wind or wind/SN ejecta scenarios.Owing to these particle acceleration scenarios, Wd 1 has become a promising target for VHEγ-ray observations. Here we present spectral and morphological results of H.E.S.S. observationsof Wd 1 performed from 2004 to 2008 and discuss the origin of thedetected, degree-scale VHEγ-ray emission in the context of different particle acceleration mechanisms.