* The State Opening of Parliament: This is an annual event where the Queen delivers a speech outlining the government's legislative agenda.
* Her Coronation: This is the ceremony where she was crowned as Queen.
* Other formal ceremonies: These might include state visits from foreign dignitaries, or other major national events.
The crown is a symbol of the Queen's authority and is not worn on a daily basis. It's a heavy and valuable object, and it's kept securely in the Tower of London when not in use.
It's important to note that Queen Elizabeth II passed away in September 2022 and was succeeded by her son, King Charles III. While the crown is a symbol of the British monarchy, it is passed down to the next monarch. So, King Charles III would wear the crown during his reign, on the same occasions mentioned above.