  The MicroMegas technology was selected by the ATLAS experiment at CERN to be
adopted for the Small Wheel upgrade of the Muon Spectrometer, dedicated to
precision tracking, in order to meet the requirements of the upcoming
luminosity upgrade of the Large Hadron Collider. A large surface of the forward
regions of the Muon Spectrometer will be equipped with 8 layers of MicroMegas
modules forming a total active area of $1200\,m^{2}$. The New Small Wheel is
scheduled to be installed in the forward region of $1.3<\vert \eta \vert <2.7$
of the ATLAS detector during the second long shutdown of the Large Hadron
Collider. The New Small Wheel will have to operate in a high background
radiation environment, while reconstructing muon tracks as well as furnishing
information for the Level-1 trigger. The project requires fully efficient
MicroMegas chambers with spatial resolution down to $100\,{\mu}m$, a rate
capability up to about $15\,kHz/cm^{2}$ and operation in a moderate (highly
inhomogeneous) magnetic field up to $B=0.3\,T$. The required tracking is linked
to the intrinsic spatial resolution in combination with the demanding
mechanical accuracy. An overview of the design, construction and assembly
procedures of the MicroMegas modules will be reported.
