The location (red dot) of C-4 on the First Class Accomodation Plan
Cabin C-4 was a First Class cabin on the Titanic, on C-Deck, against the bulkwark of the forward part of the lenghty section of the Deck. The stateroom was placed in a row of other cabins at the front, between C-6 and C-2. There was a porthole that could look over the bow of the ship. It doesn't seem there was anyone staying in the cabin at the time of the Maiden Voyage.
The room had a standardized interior and was meant for two passengers, with an extra Pullman upper berth when required, should a third person want to stay.