The castle in Act 2 could look like this. Spiral staircase leading to the "stage" where princess, prince, and Rusalka have their quarrel. Rusalka runs down the steps to the fishpond. Castle is located up high near the moon to imply that being with the prince is a far-fetched dream.
Wiccan or Celtic Paganism: Some Basic Differences - Although I respect all beliefs, and I feel it is alright to use some Wiccan terms and ideas in Pagan practices (especially if, like me, you celebrate Sabbats and Esbats with a group of varied and eclectic witches,) it is still important to understand the differences!