A State Memorial in Wellington today will mark the death of Queen Elizabeth II, the longest reigning monarch in British history.

The service will be held during a national day of mourning and will begin at 2pm in Wellington Cathedral of St Paul.

St Paul's first foundation stone was laid by the Queen during her first visit to New Zealand in 1954. The cathedral still holds the royal prayer books used by the Queen in 1954, the cover of which is embroidered with pōhutukawa and kōwhai flowers.

The service will begin with a national minute of silence and be led by the cathedral's acting dean, Reverend Katie Lawrence, and will contain ceremonial elements such as the parade of the Queen's Colours as well as karakia and hymns.

The public memorial for Queen Elizabeth II will be broadcast on a screen at Parliament Lawn in Wellington. Photo / Aaron Dahmen

Prime Minister Jacinda Ardern will read an extract from the Royal Visit to New Zealand, which was published following the Queen's first visit to Aotearoa New Zealand. The extract describes the departure of the Queen and the Duke of Edinburgh from New Zealand.

Governor-General Dame Cindy Kiro will also speak at the service, and reflect on the late Queen's life of service and her relationship with the country.

There will be a reading from St Mary's College head girl Erana Ngarimu and a pictorial montage of the late Queen accompanied by the Choir of Wellington Cathedral of St Paul.

Then, the national anthem God Save the King will be sung by all before the Queen's Colours and Personal Flag for New Zealand are marched out of the Cathedral.

The service is closed to the public but will be screened outside Parliament at a free, family-friendly event.

• Queen Elizabeth II Memorial Day: What you need to know

While Wellington is holding the national memorial there are other services going on around the country including in Auckland and in Christchurch.