  The alignment of tracking detectors is crucial for the physics programme at
the LHC, especially for precision measurements like the W mass. The alignment
of the ATLAS silicon tracking detectors with a total of 5832 modules poses an
unprecedented challenge. In this poster, two track-based alignment algorithms
at ATLAS will be covered: the Global chi^2 Algorithm based on chi^2
minimisation, and the Robust Alignment Algorithm based on centering residual
distributions. On a time scale of minutes and hours, the geometry of the
silicon tracking detectors can be monitored with the Frequency Scanning
Interferometry system. An overview of this system will also be given.
