After you've beaten the game, a new area called the Golden Temple will appear on the map. However, you can't enter it immediately; in order to open the door, you need to collect eight Rare Orbs. To find the Orbs, you must go back and collect the K-O-N-G letters in each level, then complete the special temple level in each section of the map. Alternatively, you can visit each of Cranky Kong's shops and buy an Orb for 50 coins a piece.