  We present the optical and X-ray study of the ultraluminous X-ray source
(ULX) NGC 5474 X-1. The X-ray spectrum taken during the bright state of the
source ($L_X \sim 2\times10^{40}$ egs/s) shows signatures of a broad absorption
line at $\simeq 8$ keV which may be a cyclotron resonant scattering feature.
This implies that this system may host a neutron star with a magnetic field
$\sim 10^{12}$ G. The first observation of this area with the Hubble Space
Telescope (HST) carried out 14 months later revealed that the source was bright
in the optical range as well. The subsequent observations have shown that the
source faded in both ranges (more than $2.8^m$ in the U band and by a factor of
50-100 in X-rays) and has never become bright again. Deeper HST observations
made it possible to impose constraints on the donor star spectral class and
mass ($<\,7$ M$_\odot$), as well as to identify a stellar cluster of about 1
Gyr, the centre of which is located at a projected distance of $\simeq 2$ pc
from NGC 5474 X-1. The ULX can be a member of this old cluster, however, the
presence of stars with ages of $\sim10$ Myr within 300 pc around the ULX does
not completely exclude the possibility that it is just an accidental
projection.
