The July 14--16, 2000 (Bastille Day) event was marked by an extraordinary level of geomagnetic activity following the impact of a large magnetic cloud onto the Earth's magnetosphere at 14:38 on July 15, 2000. The strong increase of the solar wind speed, and density and the large amplitude and variability of By and Bz gives rise to dramatic topological changes of unexpected magnitude in the magnetic field of the near-Earth magnetosphere. This event is one of the first real events comprehensively modeled with the adaptive grid MHD simulation scheme BATS-R-US. Magnetic field line integrations were performed with the model output to obtain the three-dimensional magnetic topology and the magnetic mapping between the northern and the southern hemisphere of the Earth.