The "Deck of Cards" is the nickname for the steep terrace of brightly painted houses on West View, just west of St Colman's Cathedral. Each house sits a step lower than the one beside it, so the row looks like a hand of cards fanned down the hill, with the cathedral spire rising behind.
It's purely a photo stop, but it's the picture of Cobh. The best angle is from the bottom of the slope, looking up the row toward the cathedral.