Tout Quarry on Portland has recently (in 2012) come under the management of the Dorset Wildlife Trust. Also known as Tout Quarry Sculpture Park it was once a working quarry for the extraction of Portland stone but has been redundant for some time now. In the early 1980s it became a sculpture park but many of the early sculptures lasted only for a year or two; that said, some remain. Work is underway to restore the habitat for nature as it has become somewhat over run with invasive species such as cotoneaster and buddleia.
If you visit Tout Quarry you will get four things; lots of flowers (including the Portland spurge) and insects, see the history of Portland stone extraction, look at some of the sculptures that remain and fantastic views of Chesil beach and beyond. Where is there another place that can give you all that! There is no doubt that the flora and fauna will improve given time when those invasive species are gone but it is still well worth a visit now. Although it takes an expert to tell them apart and name them do take time to look and wonder at the lichens on the rocks.
Just a word of caution. Away from the main tracks the going can be a bit difficult on loose stone chippings and some steep drops. In addition, the main path around the sea cliff has had to be closed due to recent erosion and land slips. That said, do thake the chance to wander in amongst the craggy gullies where the limestone has been removed, all sorts of things can be found there.