This is a huge grassy part of the Gardens that's devoted to big outdoor concerts, opera, film festivals etc. It's loads of fun to go with friends to one of these events. Mostly happening in the summer. I saw the Sydney Symphony play, saw an opera and have also attended Tropfest for several years. This is the biggest outdoor short film festival in the world. But, go early in the day and camp out with friends, food and wine to get a good spot for the films!