Another is https://www.edenproject.com/

   “ We bought an exhausted, steep-sided clay pit 60 metres deep, with no soil, 15 metres below the water table, and essentially gave it life. Into it we brought a huge diversity of plants that we use every day but often don’t get to see, planted in soil made from ‘waste’ materials, watered by the rain, in giant conservatories and buildings that drew inspiration from nature. Behind this vision a dedicated team was brought together – made up of people who wanted to change something, who wanted to be able to say, ‘I’m glad I did,’ rather than, ‘I wish I had.’”

Quite an expensive project, but interesting to learn from.