Church ceremony or civil wedding?
Ms Markle has been married before, but can still have a church wedding.
The Church of England agreed in 2002 that divorced people could remarry in church under certain circumstances.
But because the Church views marriage as being for life, there is no automatic right to do so and it is left to the discretion of the priest.
When Harry’s father, the Prince of Wales, married Camilla Parker Bowles - both divorcees - their civil ceremony took place in Windsor’s town hall. The Queen did not attend, but went to the religious blessing afterwards.
But Charles’s choices were restricted. He is a future king who will one day be Supreme Governor of the Church of England, whereas Harry is not.
St George’s Chapel, Windsor Castle
St George’s is the most likely option for Harry and his new fiancee.
The 15th century gothic church set in the Lower Ward of Windsor Castle is a popular choice for royal weddings. Charles and Camilla had their televised blessing there in 2005 after their civil ceremony.
It would offer Harry and Ms Markle a slightly more intimate, lower key venue, but one that is still appropriately royal.
It usually holds around 800 guests, whereas Westminster Abbey - where the Duke and Duchess of Cambridge wed - can accommodate 2,000.
The church - a place of worship for the Sovereign and the Royal Family - is often at the heart of royal events.
With the Queen now 91 and the Duke of Edinburgh 96, the choice would be especially convenient for Harry’s ageing grandparents, who spend a great deal of time at home in the castle.
Surrounded by the Horseshoe Cloisters and the Henry VIII gate, the venue will also provide the Royal Family with a certain amount of privacy on the day of the wedding.
Harry was also christened in the chapel in December 1984 when he was three months old, which, according to Church of England rules, means he can also marry there.
His uncle, the Earl of Wessex, married Sophie Rhys-Jones, now the Countess of Wessex, in St George’s in 1999, while Harry’s cousin, Peter Phillips, wed Autumn Kelly there in 2008. Newlyweds and their families traditionally pose for photographs afterwards on the vast west steps.
The historic church - started by Edward IV and finished by Henry VIII - is the resting place of 10 monarchs including Henry VIII and his third wife, Jane Seymour, and the beheaded Charles I.
It has also been the setting for many historic funerals. The Queen Mother’s private committal service took place there following her Westminster Abbey funeral in 2002 - the same year as Princess Margaret’s small, private funeral.
Like Westminster Abbey, the chapel is known as a Royal Peculiar, with the Dean of Windsor responsible only to the Sovereign.
Harry and Ms Markle’s reception could be held in the castle’s 180ft (55m) long St George’s Hall, traditionally used for state banquets. The vast hall had to be restored following the devastating fire at the castle in 1992.
St Paul’s Cathedral
If Harry and Ms Markle decide to opt for a large-scale royal wedding with the full works, they could pick London’s St Paul’s Cathedral.
With room for more than 2,000 guests, the grand, opulent central venue, with its distinctive black and white chequered floor, would have the advantage of providing an alternative setting to William and Kate’s wedding in Westminster Abbey.
But it would be a poignant choice for Harry.
His parents, the Prince of Wales and Lady Diana Spencer, wed in Sir Christopher Wren’s famous domed landmark on July 29 1981.
It has been the focal point for many a royal celebration including Queen Victoria’s Diamond Jubilee, the 80th and 100th birthdays of the Queen Mother and the thanksgiving services for the Queen’s Golden and Diamond Jubilees.
A cathedral dedicated to St Paul has stood on site since 604 AD. The current building - the fourth to occupy the site - was designed by the court architect, Sir Christopher, and built between 1675 and 1710 after its predecessor was destroyed in the Great Fire of London.
A key part of London’s skyline and a popular location with tourists, it is the cathedral of the Diocese of London. It staged the funerals of Lord Nelson, the Duke of Wellington, Sir Winston Churchill and, in April 2013, Baroness Thatcher.
Harry and Ms Markle could follow William and Kate’s lead. The gothic abbey is well-rehearsed at staging important royal ceremonies.
A short distance from Buckingham Palace, the central London location is convenient and the interior of the abbey is impressive.
Harry’s grandmother, the Queen, and great-grandmother, the Queen Mother, were both married at Westminster Abbey.
But it is also where Harry attended his mother’s funeral when he was just 12 and holds some painful memories for the prince.
The couple could ditch the UK entirely and head abroad for their nuptials. Ms Markle is American and made a home in Toronto, Canada, She and Harry also both share a love of Africa.
But such a decision would create a raft of problems, especially for an elderly Queen and Duke of Edinburgh.
Harry will want his nonagenarian grandparents to be there and is unlikely to ask them to make a long and tiring journey across the world to see him wed.
Also, the logistical and security considerations of staging a royal wedding abroad would be immense.
It would be an unpopular move - the cost of royal security falls to the taxpayer. - and royal weddings on home soil boost the British tourist industry. In 2011, the year William and Kate married, a record number of foreigners holidayed in the UK.
However, Harry and Ms Markle might head abroad for an extended post-wedding party with friends.
Harry has plenty of friends whose families own stately homes which could be commandeered for the celebration.
They might even follow in the footsteps of Zara and Mike Tindall, who went to Scotland, marrying in Edinburgh’s Canongate Kirk and holding the reception at the Palace of Holyroodhouse.
As an outside bet, the Church of St Mary Magdalene, Sandringham, close to the Queen’s much-loved private Norfolk retreat, is regularly used as a place of worship by the royals, particularly on Christmas Day.
The pretty country church, which dates back in its present form to the 16th century, might be the perfect choice for a small, intimate wedding if Harry and Ms Markle decide to keep their actual ceremony private on the big day.
London’s Guards’ Chapel at Wellington Barracks is the religious home of the Household Division, and would have military connections for ex-soldier Harry, who served in the Blues and Royals regiment of the Household Cavalry.
But it is also where Camilla married her first husband, Andrew Parker Bowles, in 1973.