Emerging from the exit of Tower Hill underground station takes you straight to one of the most famous sights in the capital of Britain – the Tower of London.

Murderous and magnificent, horrendous and heroic, it is lit on a mild, dry, low-cast morning by a pale, silver sun and surrounded by a wide, deep moat.

And since August this year this moat is attracting as many visitors as the Tower itself as it hosts the temporary installation Blood Swept Fields and Seas of Red.

One hundred years ago, men and boys marched off to a war that was to be over ‘by Christmas’. This was not the case.

Four years later victory was finally dragged from the seas, skies and terrible trenches at the cost of 888,246 British and colonial lives.

This loss is remembered each year at 11am on the 11th day of the 11th month, with wreaths of poppies, the first flower to bloom again on the battle-scarred French and Belgian fields.

And the centenary of the start of this great war is being marked in a very particular way using the symbol of those same poppies, in a setting that represents the history of Britain’s defences.

Today, more than 18,000 volunteers, civilians, service men and women of all ages are continually assembling and ‘planting’ large ceramic poppies, one for each of the fallen from the great war, in a simple but stunning display.

A scarlet river of poppies fills the moat. But what makes this so special is that it is a work in progress and will continue to November 11.

Visitors young and old, from every continent and all walks of life, stroll the length of the moat walls and railings in their own time, reading the information plaques, taking photographs or gazing thoughtfully at the activity below.

The only sounds are low voices and the dull clinking of the hammers staking the poppies in the earth.

There are no intrusive voice-overs, music, audiovisual screens or guides. Even the planes and traffic seem muted.

The Shard building can be seen on the horizon.

This exhibition speaks for itself. The heavy, grey walls of the Tower, the green grass of the moat flooded with thousands of poppies and, in the distance, that controversial, glass skyscraper The Shard, a building those honoured here could never have imagined, rises in hope for the future.

The poppy installation will be dismantled from November 11 and the poppies are being sold for £25 with the funds going, naturally, to service charities. But you still have a chance to take it all in.

We have all benefited from the sacrifices made by those represented at this centen-ary event.

Today, costly conflicts go on and we owe a debt to those who defend the peace and freedom we value so much.

Of all the sights of London you may be heading for, to visit at this time and not include the poppy tribute would be to miss a once-in-a-lifetime sight that says so poignantly that we do remember them, today more than ever.

For more details, images and stories behind this extraordinary creation, visit http://poppies.hrp.org.uk or search for ‘Tower of London poppies’ on Google.