  The ATLAS detector at CERN's Large Hadron Collider (LHC) is equipped with a
tracking system at its core (the Inner Detector, ID) consisting of silicon and
gaseous straw tube detectors. The physics performance of the ID requires a
precision alignment; a challenge involving complex algorithms and significant
computing power. The alignment algorithms were already validated on: Combined
Test Beam data, Cosmic Ray runs and simulated physics events. The alignment
chain was tested on a daily basis in exercises that mimicked ATLAS data taking
operations. ID commissioning after final installation into the ATLAS detector
has yielded thousands of reconstructed cosmic ray tracks, which have been used
for an initial alignment of the ID before the LHC start-up. A hardware system
using Frequency Scanning Interferometry will be used to monitor structural
deformations. Given the programme outlined here, the ATLAS Inner Detector has
had a solid preparation for LHC collisions.
