On the skyline above Matlock you can glimpse Riber Castle. Apparently the ridiculously wealthy developer of Matlock Hydro, Mr Smedley, built this originally as nothing more than an eyecatcher, then when he received public derision for this announced he always intended to live in it and had to build the rest of the castle on the back of the facade. Sadly there was no water supply on top of the hill and so it wasn't a practical dwelling until long after Mr S abandoned it. It became a school and finally a zoo; various urban exploration groups have had a poke around but the building is at last in the process of being converted into luxury apartments so you can't get very close any more. Very dramatic.
Wingfield Manor was a real surprise. 'Neither the picturesque nor the strictly architectural traveller should miss it', says Pevsner, waxing lyrical about its fifteenth-century ruins. I drove through the village of South Wingfield and wondered why there was no sign to it. Having crossed a cattle grid and then driven carefully up a rough track I found out why: although administered in some way by English Heritage, it's still part of a farm and admission is only by guided tour. However you only discover that on the EH website (as I just have). I couldn't find anyone there, and the farm itself doesn't show any clear signs of current activity, the yard being full of rusting machinery and surrounded by derelict buildings.
Sir William Boyd Dawkins, redoubtable Victorian and Edwardian naturalist and geologist, so they've decided to recreate his study in the museum. It's fantastic, just the sort of room any gentleman would be proud to have. There's even a top hat.
Derbyshire Black Marble until I had a look around Buxton Museum.