Dressageworld.de hosts a beautiful photo gallery of Baroque horses, shot by Cristiane Slawik. The horses are posed in the grounds and gardens of a fabulous estate - does anyone know where? - and the riders are in historic costumes. There are a lot of photos of women in historic sidesaddle costume included in this set.
Site is in German, but the captions on the photos mostly name the rider, the horse, and the movement they are doing, in that order, so you can enjoy anyway.