  Using photometric and spectroscopic observations of the double-lined
early-type eclipsing binary system ALS 1135, a member of the distant OB
association Bochum 7, we derived the new physical and orbital parameters of its
components. The masses of both components were derived with an accuracy better
than 1 per cent, their radii, with an accuracy better than 3 per cent. Since
the primary's mass is equal to about 25 sun masses, its radius was subsequently
used to derive the age of the system which is equal to 4.3+/-0.5 Myr. The
result shows that this method represents a viable alternative to isochrone
fitting.
  A photometric search of the field of ALS 1135 resulted in the discovery of 17
variable stars, including seven pulsating ones. One of them is an SPB star
belonging to Vel OB1, the other six are delta Scuti stars. Of the six delta
Scuti stars three might belong to Vel OB1, the other two are likely members of
Bochum 7. Given the age of Bochum 7, these two stars are probably pre-main
sequence pulsators. In addition, we provide UBVI_C photometry for about 600
stars in the observed field.
