One of the many difficulties of presenting a historic building to the public is how to deal with the accessories and installations of modern heating, lighting, safety and security devices. These are invariably white and made from some clearly modern material -- not the easiest objects to blend in sympathetically with even a 19th century interior, much less a Renaissance one.
The usual curatorial device is to camouflage light switches, power points, smoke detectors and radiators with a trompe l'oeil paint job. It's fairly tacky if you look closely, but, especially for really anachronous things like smoke detectors, high up on the ceiling and painted to blend in with the surrounding decor, it works well enough. Of course, the bigger the object and the closer it is to eye level, the less pleasing the result.