Cherbourg-Octeville is a large city at the North of the Cotentin/Normandy Peninsula. Driving off the Ferry, we followed google directions and ended up in Octeville, eventually circling back to the D901, which we would have found very much more easily by ignoring google. Alternatively, it may be possible to avoid the town altogether by turning LEFT out of the Ferry area and finding the N13, all the way down the coat to Bayeux and beyound.
Cherbourg has a very extensive history (best to consult Wikepedia) but most folk drive straight through and into France proper. Behind the Regency Hotel on the inner harbour, there are numerous winding streets in the old quarter, along with cafes, shops and a pleasant large square.