From Kensington Society : Wayfinding in British Heritage Monuments

Over the past couple of weekends, I have been lucky enough to explore a number of amazing British Heritage sites across the country. While each site is unique in what occupies the land, the signage, wayfinding, and branding are unified across them all--providing a very convenient and satisfying visit. All the signs use solid san serif fonts, which are clear and readable. Most use the black and white motif of the last sign from Stonehenge, which has a good amount of contrast and again contributes to the readability. However, as you can see from the two castle information signposts, in an effort to color-code, there is a loss of contrast (especially the yellow and white sign) which makes them less readable.

I'll post pictures of the actual castles tomorrow, hopefully!