Here's a handy guide to what you'll see en route.
You'll begin queuing in Southwark Park, south east London. When I was there earlier, the sign was warning of a 14 hour queue. You'll have lots of time to take in what's around you. Here are a few highlights and fun facts.
After about 10 minutes you'll find yourself down by the river at Bermondsey. You'll be walking alongside the river Thames for the entire route.
The River Thames
The Thames is the entire reason why London exists and the Roman's settled here over 2000 years ago. It's 215 miles long and flows through 9 counties, its source being in Kemble, Gloucestershire. A few years ago I walked the whole thing from the 'Sea to the Source'. It was once a tributary river of the Rhine in Germany (when we were still landlocked to the rest of Europe). In central London the Thames has a tidal change of about 23ft, so see if you can see any 'mudlarks' looking for things that have washed up. It's basically a massive archaeological site and in the 19th century a politician called John Burns referred to it as 'liquid history'.
The City of London
From this point on the river you'll see the City of London opposite. It looks very modern but was the Roman city of Londinium founded in about 48AD. It's the original financial district. You'll see a number of tall buildings including 'the Gherkin' (No. 30 St Mary's Axe) and the 'Walkie Talkie' (20 Fenchurch Street).
Fun Fact - During the hot summer of 2013 (a year before completion) the 'Walkie Talkie' acted as a massive magnifying glass and was melting and scorching things including a car parked on the street below. The architect Rafael Vinoly said "it's not my fault, the sun was in the wrong place".
You'll also get your first glimpse of:
Undoubtedly one of the most iconic structures in London, Tower Bridge was completed in 1894. It's a 'bascule' bridge allowing the road to lift to allow ships through and is actually a steel structure with stone cladding.
Fun Fact - The winning design was chosen as part of a competition, judged by architect Horace Jones. He chose his own design as the winner.
St Saviour's Dock
You'll pass around where one of London's subterranean rivers, the Neckinger meets the Thames. In the 17th and 18th century it became known as Jacob's Island, a notorious place of execution. In 1838, Charles Dickens described the area as "the filthiest, the strangest, the most extraordinary of the many localities hidden in London".
Fun Fact - The name is thought to derive from 'devil's neckcloth' in reference to the nooses used to hang people here.
Next you'll pass through old riverside warehouses, once used to unload the myriad of goods that arrived in London from across the globe and now turned in to super duper apartments. You'll pass beneath the south side of Tower Bridge which is where all the engine rooms are housed, as originally the bridge was powered by coal furnaces.
Fun Fact - Tower Bridge has its own mortuary on the north side of the river, where bodies from the river were pulled out.
Tower of London
As you pass City Hall, on the other side of the river you'll see the Tower of London. It's actually 21 separate towers, but the White Tower in the centre dates back to 1090, a couple of decades after the Norman conquest.
Fun Fact - The Tower was London's first zoo. From the 1200s until 1835, animals given to monarchs as gifts were housed there, with the public paying to see them.
A WW2 ship that was used during D-Day in 1944. It has been a museum open to the public for over 50 years.
Fun Fact - If the guns on the front were to fire they'd hit a service station on the M1 motorway (over 12 miles away).
The original London Bridge opened in 1209 and was the longest inhabited bridge in the world. It remained there until the early 1800s. The bridge you're passing is the third on the site and opened by the Queen in the early 1970s.
Fun Fact - The 2nd London Bridge was sold to an American called Robert P. McCulloch who shipped it over to Arizona and created a man-made lake around it called Lake Havasu and made it into a tourist attraction.
Next you'll pass Southwark cathedral which was founded in the early 12th century. It's a beautiful church, originally called the Collegiate Church of St. Saviour and Mary Overie. The 'Overie' was short for 'church over the river'.
Fun Fact - William Shakespeare's younger brother Edmund was buried there in 1607.
You'll pass by a replica of Francis Drake's galleon, the 'Golden Hind' which left to circumnavigate the world in 1577, returning to Deptford (near where you started queuing) in 1580. They were really pirates, but we called them privateers to make us feel better.
Fun Fact - The ship was originally called 'the Pelican' but its name changed during the journey in honour of one of the main financiers, Christopher Hatton whose family emblem was the golden hind (a female red deer).
You'll pass the remains of the 14th century palace of the Bishop of Winchester who once had jurisdiction over the area. The imposing wall and its rose window were discovered after a warehouse fire in the 19th century.
Fun Fact - The area of Bankside in the Elizabethan period was known as the 'City of Sin' as it housed the brothels and theatres. The church made money from the prostitutes and the women were known collectively as 'the Bishop of Winchester's Geese'. To be 'bitten by a Winchester Goose' meant you had contracted a sexually transmitted disease on Bankside and features in one of Shakespeare's plays.
Shakespeare's Globe Theatre
Finished in the late 1990s by American Sam Wanamaker, Shakespeare's Globe Theatre is a recreation of an Elizabethan Theatre and memorial to the bard. The original site is actually on the street behind.
Fun Fact - It has the only thatched roof in central London (after thatch was banned following the Great Fire of London in 1666).
Tate Modern and Millennium Bridge
The Tate Modern was a 1960s power station built by Sir Giles Gilbert Scott, who also designed the now iconic red telephone boxes. It's now a modern art gallery.
The Millennium Bridge opened in the year 2000 and is a pedestrian foot bridge that joins the Tate Modern to St Paul's cathedral in the City.
Fun Fact - The Millennium bridge was open for 2 days and closed for 2 years because it had a massive wobble. It will be forever known as 'the wobbly bridge'.
Blackfriars Bridge & Blackfriars Railway Bridge
The Victorian pedestrian and traffic bridge gets its name from the monastery that stood on the north side until the 16th century. It was run by Dominican monks who wore black, hence the 'blackfriars'.
The railway bridge leads in to Blackfriars station and Underground station which is the only underground station in London to have exits on either side of the Thames.
Fun Fact - The railway bridge has solar panels on the roof which generates half the electricity for the station. It's the largest solar powered bridge in the world.
The National Theatre
Founded in 1963 by Sir Lawrence Olivier (you'll pass a statue of him outside), the current brutalist building opened on this site in the late 1970s. The new King Charles III once said "it's a clever way of hiding a nuclear power station in the middle of London without anyone objecting."
Waterloo Bridge was bombed at the beginning of WW2, rebuilt largely by women and therefore nicknamed 'the ladies bridge'.
The area now known has the Southbank was destroyed in WW2. It was rebuilt to house arts venues such as the Queen Elizabeth Hall, the Hayward Gallery and the Royal Festival Hall, the first building to open here in 1951.
The London Eye
Opened as 'the Millennium Wheel' in the year 2000 and renamed the 'London Eye'. It takes 30 minutes to go all the way around.
Fun Fact - It has 32 pods. Each one represents one of London's 32 boroughs.
Westminster Bridge and the Royal Palace of Westminster
Westminster Bridge is painted green, the same colour as the benches in the House of Commons.
The medieval Palace of Westminster burnt down in 1834. A few bits survived including the Great Hall, where the Queen is Lying-in-State. It was rebuilt by architect Charles Barry and completed in 1870. 'Big Ben' is actually called the Elizabeth Tower and the tower on the opposite end is called the Victoria Tower which houses documents and bills of parliament dating back to the 14th century.
Fun Fact - Big Ben is the name of the 14 tonne hour bell, not the tower.
Lambeth Palace has been home to the Archbishop of Canterbury since the 1200s. The oldest part of the current building dates back to the 15th century.
Fun Fact - Behind those walls is a garden of just over 10 acres, making it one of the oldest and largest private gardens in London.
Lambeth Bridge was completed in 1932 to replace a Victorian Bridge. It had originally been the site of a ferry that took horses across the Thames, which is why the road on the opposite bank is called Horseferry Road. You'll notice the paintwork is largely red, the same as the benches in the House of Lords.
Once you've crossed Lambeth Bridge, you'll be on the final stretch before you enter the Great Hall to see the Queen Lying-in-State.
Bowl Of Chalk
Bowl Of Chalk based shenanigans.