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.

Kate made a "strictly private" visit in December o personally deliver gifts to the people involved in her treatment.

Kate Middleton visited the Royal Marsden Hospital in London on Tuesday, Jan. 14, where she received chemotherapy treatment after her cancer diagnosis last year. See all the photos here

The Princess of Wales wanted to “show her gratitude to the incredible team, but also highlight the world leading care and treatment the Marsden provides.”

Kate Middleton has made an emotional visit to the Royal Marsden Hospital in London to personally thank staff who took care of her during her cancer treatment last year. Dressed in a long brown checkered coat atop a maxi burgundy dress,

Kate, the Princess of Wales, made a poignant return Tuesday to the same hospital where she received treatment after being diagnosed last year with cancer.

Middleton announced the happy news on her Instagram Tuesday alongside photos from her surprise hospital visit to the Royal Marsden Hospital in London.

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.

The Princess of Wales went on holiday in the Alps sometime after spending Christmas with the royal family at Sandringham