These three pictures were taken from a boat along the coast near Duino, Trieste (Adriatic Sea, NE Italy), on 12 January 2001 by Kajetan Kravos and Silvano Candotto. The bird appeared as a Great Black-backed Gull for both its size (since it seemed greater than the Yellow-legged Gulls, Larus michahellis, flying around) and its heavy bill. It is really a dark immature large gull.
It's neither an American Herring Gull, Larus argentatus smithsonianus (the head is too white, and its shape doesn't fit; there appears to be very little barring on the lower belly and under tail coverts, which should be heavily barred in smithonianus. The scapulars also appear to be too dark) nor a Great Black-backed Gull, L.marinus ( head shape, primaries, secondaries and tail color dont fit).