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.

Princess Kate stepped out on a solo visit today to the Royal Marsden Hospital in Chelsea, where she received treatment for her own cancer diagnosis last year. The Princess of Wales, 43, arrived on Tuesday to speak to staff and patients at the hospital, which her and Prince William have now become royal patrons of.

The Royal Marsden in London, where the Princess of Wales underwent treatment, is one of the world’s leading cancer hospitals.Rated outstanding by the regulator the Care Quality Commission (CQC), it has an international reputation for research and thrives on pioneering the use of cutting-edge cancer treatments.