Kate Middleton didn't wear her engagement ring that once belonged to Princess Diana at the Royal Marsden Hospital in London on Jan. 14. Inside why and more about Princess Kate's new ring.

The Princess of Wales made a surprise return to the Royal Marsden Hospital to personally thank staff who looked after her during her cancer treatment on Tuesday. At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.

Kate Middleton opted for one of her go-to colors during a visit to The Royal Marsden Hospital in London on Tuesday. The Princess of Wales and her husband, Prince William, are joint patrons of The Royal Marsden NHS Foundation Trust. Middleton received treatment from The Royal Marsden during her battle with an undisclosed form of cancer.