  In this paper, we report the production cross-section of forward photons in
the pseudorapidity regions of $\eta\,>\,10.94$ and $8.99\,>\,\eta\,>\,8.81$,
measured by the LHCf experiment with proton--proton collisions at $\sqrt{s}$ =
13 TeV. The results from the analysis of 0.191 $\mathrm{nb^{-1}}$ of data
obtained in June 2015 are compared to the predictions of several hadronic
interaction models that are used in air-shower simulations for
ultra-high-energy cosmic rays. Although none of the models agree perfectly with
the data, EPOS-LHC shows the best agreement with the experimental data among
the models.
