  The Local and Loop I superbubbles are the closest and best investigated
supernova (SN) generated bubbles and serve as test laboratories for
observations and theories of the interstellar medium. Since the morphology and
dynamical evolution of bubbles depend on the ambient density and pressure
distributions, a realistic modelling of the galactic environment is crucial for
a detailed comparison with observations. We have performed 3D high resolution
(down to 1.25 pc on a kpc-scale grid) hydrodynamic simulations of the Local
Bubble (LB) and the neighbouring Loop I (L1) superbubble in a realistically
evolving inhomogeneous background ISM, disturbed already by SN explosions at
the Galactic rate for 200 Myr before the LB and L1 are generated. The LB is the
result of 19 SNe occurring in a moving group, which passed through the present
day local HI cavity. We can reproduce (i) the OVI column density in absorption
within the LB in agreement with COPERNICUS and recent FUSE observations, giving
N(OVI) <2 10^{13} cm^-2 and N(OVI)<7 10^{12} cm^-2, respectively, (ii) the
observed sizes of the Local and Loop I superbubbles, (iii) the interaction
shell between LB and L1, discovered with ROSAT, (iv) constrain the age of the
LB to be 14.5+0.7/-0.4 Myr, (v) predict the merging of the two bubbles in about
3 Myr, when the interaction shell starts to fragment, (vi) the generation of
blobs like the Local Cloud as a consequence of a dynamical instability. We find
that evolving superbubbles strongly deviate from idealised self-similar
solutions due to ambient pressure and density gradients, as well as due to
turbulent mixing and mass loading. Hence, at later times the hot interior can
break through the surrounding shell, which may also help to explain the
puzzling energy "deficit" observed in LMC bubbles.
