Find out how the US honours its fallen with the mesmerising Changing of the Guard
An extraordinarily intricate ceremony takes place every day at Arlington National Cemetery in Virginia that can fill those who witness it with pride and emotion.
Every hour on the hour between 1 October and 31 March, and every half hour between 1 April and 30 September, visitors to the Tomb of the Unknown Soldier can see the Changing of the Guard.
The ceremony involves the handover of responsibility between the Tomb Guards, the majority of whom have the title of Sentinel.
The impressive display honours those who served in the armed forces and made the ultimate sacrifice for their country.
Videos of the ceremony have accumulated several million views, with one in particular reaching 14 million.
After watching the routine below, one YouTube user was moved to say: "The amount of precision and fluidity of their movements and the thoroughness and exactness with which he examines the rifle would make a samurai impressed."
How does the US pay its respects to its military dead?
The Tomb of the Unknown Soldier has been a central part of Arlington National Cemetery for more than 100 years.
It serves as a focal point for those whose loved ones died and have no known grave, meaning there is no permanent resting place to honour their memory.
The Tomb of the Unknown Soldier has been guarded 24 hours a day, every day, since 2 July 1937.

However since 1948 it has been the job of soldiers from 3rd US Infantry Regiment, affectionately known as The Old Guard, to watch over the tomb.
Tomb Guards must keep a constant vigil while displaying the high standards and traditions of the US Army.
They are also responsible for protecting the iconic memorial from any desecration or disrespect.

Those tasked with guarding the tomb undergo rigorous training and examinations to earn this highly regarded position.
There are six different levels of responsibility at the tomb – Sentinel, Assistant Relief Commander, Relief Commander, Assistant Sergeant of the Guard, Sergeant of the Guard and Platoon Leader or Commander of the Guard.
Sentinels are the youngest, aged about 22, and arguably have the hardest job as the role takes a huge toll on their bodies.
What is it like to be a Tomb Guard?
Harold Earls, a retired US Army captain and a former Commander of the Guard, spoke in March 2020 during the height of the Covid-19 pandemic about the unique tradition.
He explained: "For us it doesn't matter if it's Christmas morning, if it's a hot day, a cold day, if it's thunderstorms, if it's raining, if it's a hurricane or if it's a Coronavirus, we're always here, we are always guarding.
"When we feel closest to the unknowns is when no one's here.
"It's in the middle of the night when we're still guarding at 2am.
"It's when a blizzard is going on and no one's here, or when it's incredibly hot.
"For us that's when it's very personal.
"I feel like after serving here over a certain amount of time you honestly feel like you have a connection to our nation's past because you feel like you are connected to them.
"I think it's important for us to show to this country that we haven't forgotten. That we will never forget the sacrifices that these soldiers made."

What is the Changing Of The Guard routine?
The Changing Of The Guard takes months to perfect, but only about seven minutes to perform.
It is an incredibly precise series of manoeuvres involving intricate, careful and smooth movements.
The level of discipline needed to perform the detailed routine impresses the crowds that gather to witness the ceremony.

Dressed in an immaculate uniform - there is no room for error for the Sentinels - perfection is the only option.
One particularly captivating moment to watch is when the Relief Commander intricately inspects the M14 rifle before a Tomb Guard takes their post.
Somehow the movements manage to combine robotic accuracy with graceful elegance.
Many of the precise movements have significant meanings such as the following rule, which is described on Arlington National Cemetery's website.
It explains: "The Tomb Guard marches exactly 21 steps down the black mat behind the Tomb, turns, faces east for 21 seconds, turns and faces north for 21 seconds, then takes 21 steps down the mat and repeats the process."
The number 21 was chosen to represent the 21-gun salute – the highest national honour that is usually fired for people such as the President or members of the Royal Family.

During their off-duty hours, Tomb Guards can be found below the Memorial Display Room of the Memorial Amphitheatre.
This is where they maintain their weapons, study the history of the cemetery, which is a vital part of being a Sentinel, and lend a hand to their fellow Tomb Guards preparing for their Changing of the Guard ceremony shift.
Things you might not know about Tomb Guards
Looking pristine for their shift doesn't come easy.
On average, it takes a Tomb Guard eight hours to prepare their uniform - the duration of a full working day for many civilians.
If you take a close look at the gloves the Tomb Guards wear, you might think they are wet - and you would be correct.
They are moistened to improve the grip on the fully functional M14 rifle.
Rumours circulating online falsely state that Tomb Guards cannot swear in public, they must not drink and they cannot live away from the barracks situated under the Tomb of the Unknown Soldier.
These beliefs are incorrect.
Tomb Guards can live off base or at Fort Myer, home to The Old Guard, plus there are living quarters under the steps of the Memorial Amphitheatre where they stay during their 24-hour shifts.
If they are 21 years old or above and not on duty, Tomb Guards are allowed to drink.
And yes, they can swear, just not while on duty. Upholding the values and traditions of the US Army is of utmost importance.

The year 1996 marked a significant milestone for women in the US armed forces when Sergeant Heather Johnson became the first woman to earn the incredibly rare Tomb Guard Identification Badge - of which only about 700 have been awarded since 1958.
After volunteering for duty in June 1995, she worked tirelessly to meet the rigorous standards and earned the coveted badge the following year.
Sgt Johnson is not the only female Tomb Guard to have earned the badge.
Private First Class Jessica Kwiatkowski made history on 18 September 2023 when she became the first female infantry soldier to be awarded the Tomb of the Unknown Soldier Identification Badge.
Other women such as Sgt Danyell Wilson and Sgt Ruth Hanks have also earned the badge, but they have come from other career paths.