We combine the assumption of environmental decoherence, as the mechani
sm generating the classical (i.e. no quantum interferences) nature of
spacetime, with the limit on its other classical feature, point-like c
ontinuity, namely Planck length. As a result, quantum extended objects
with masses larger than the Planck mass have to derive their quantum
behaviour from long-range correlations; objects with masses smaller th
an the Planck mass cannot display classical behaviour.