Spectacular environments play a prominent role in Niki de Saint Phalle's unique oeuvre. The walk-in Nanas, the Stravinsky Fountain in Paris, and her Tarot Garden in Tuscany are masterful examples of this. Her last completed major project in Hanover became her artistic legacy: the grotto in the Herrenhausen Gardens, redesigned according to her plans. Built in 1676 as part of the Baroque gardens, the grotto, originally decorated with shells, crystals, glass, and minerals, once served as a summer retreat. It was restored for EXPO 2000 and subsequently redesigned by Niki de Saint Phalle in her characteristic style. This completely revised new edition of the 2003 monograph describes the history of its creation and restoration and highlights the art-historical significance of the grotto from today's perspective.