Think again my frield - these old things still exist all over the place - sometimes still housing bears but also converted for other species (eg Mandrills at Duisburg, etc).
The pits you refer to at Dudley (with exception of central Polar Bear enclosure) were originally for lions and tigers and I wouldn't really describe them as pits - even in their original incarnations.
Neither would I describe these at Napoli as pits - more like grottos (not actually much better mind)
