Christina, Duchess of Milan, (a Princess of Denmark and the niece of the Emperor Charles V, thus the great niece of Henry's first wife, Catherine of Aragon) painted by Holbein for Henry VIII, which clever woman said at the time "If I had two heads, one should be at the King of England's disposal." That she was painted full length was, apparently, most
There's another Holbein, Lady With a Squirrel (and a Starling):
which is charming, and Holbein's famously cryptic The Ambassadors:
There are a few portraits by Titian and by Antonis Mor and sculptures by Leone Leoni of ugly, charmless King Philip II of Spain (a first cousin of Christina of Milan), which manage to convey the sourness and the pomposity of the man and show the birth of propaganda in the way they are contrived to glorify him.
There's so much there and Slightlyfoxed has described some of the other good stuff. I'll just mention one more, Moroni's The Tailor:
He's a cutie. And not a noble or a monarch, so unusual that he was the subject of such a portrait. How comes a mere tailor to be wearing a ring with a big red gem set in it on the little finger of his right hand?
There's lots to see and only a few more days to go. Very stimulating stuff, well assembled and displayed. Prompted lots more questions than it answered but that's OK. I'm not an art historian, so I liked being gently introduced to the history of the portrait as I moved from room to room. There's a chronology that's clear but the arrangements are thematic, guided by the purpose of the portrait as a form at different periods.