  The production of exclusive $\gamma \gamma \rightarrow \mu^+ \mu^-$ events in
proton--proton collisions at a centre-of-mass energy of 13 TeV is measured with
the ATLAS detector at the LHC, using data corresponding to an integrated
luminosity of 3.2 fb$^{-1}$. The measurement is performed for a dimuon
invariant mass of 12 GeV $<m_{\mu^+\mu^-}<$ 70 GeV. The integrated
cross-section is determined within a fiducial acceptance region of the ATLAS
detector and differential cross-sections are measured as a function of the
dimuon invariant mass. The results are compared to theoretical predictions that
include corrections for absorptive effects.
