Five bird species (Great, Blue and Coal Tits, Redstart, Tree Sparrow) nested inside vertical metal pipes of fences in Warsaw suburbs (central Poland). It appeared to be the main breeding site for a Great Tit — nearly 80% of the nests of the local population. The preferred diameter of the pipes depended on the size of the species (mainly on the length of the tarsus). It was the widest in Great Tit and the narrowest in Blue Tit. Great Tits built their nests significantly deeper (down to 1.7 m from the top) than the other species. The mean number of fully feathered nestlings per successful nest was lower in pipes than in nest boxes. Such a nest location is a local adaptation of birds living in highly a urbanised area, where natural breeding cavities are scarce.