The monarch spent 30 minutes with the 92 year old at the London Clinic, where he is recovering after undergoing exploratory surgery on his abdomen on Friday (07Jun13).
It marked the Queen's first trip to the private medical centre to check on her husband since he was admitted last Thursday (06Jun13), but she wasn't Philip's only visitor - the royal couple's youngest son, Prince Edward, also stopped by to mark his dad's special day.
Prince Philip, the Duke of Edinburgh, is said to be "comfortable and in good spirits" and is to remain in hospital for "up to two weeks".
A spokesperson for Buckingham Palace adds, "It is expected he will then be taking a period of convalescence of approximately two months."
Earlier on Monday, guns were fired in his honour at Edinburgh Castle in Scotland, the Tower of London in the U.K. capital, Cardiff Castle in Wales and Hillsborough Castle in Northern Ireland.