The Menin Gate was extensively re-built after the First World War, along with the rest of the town of Ypres. The great arch was the scene of thousands of marching troops, who marched off to oblivion in the Ypes Salient, St. Julien, and Passchendale. Due to the nature of that particular madness, many of those men went missing. That is to say, they were killed, buried in shallow graves in "no man's land" and often subsequent artillery disturbed those graves. Thousands upon thousands of men had no memorial to their passing.
When the British, and Belgians re-built Ypres, they also re-built the Menin Gate as a sort of combination Triumphal Arch and Mausoleum. It is a gate way in the old walls of the city, and there are stairways in the middle of the walls which lead to the top of the walls. The intention was to record the names of all the soldiers who had no known grave. They discovered that even at two inches per name, there was way not enough space on the walls. The above picture shows part of the wreath laying ceremony which occurs every night at eight o'clock, rain or shine, 24-7.
Wreaths of poppies are laid here, every day, often without any ceremony. This is a view of the stairway which leads up to the top of the wall, these stairways are on both sides inside the great Menin Gate arch, and lead to the top of the walls. You will note that the names continue up the sides of the stairwells.
People visit here often, and find their grandfather's names, and often place a poppy beside the name.
The last post is played every night here, and has become a tourist attraction in its own right. Hitler refused to damage this monument in any way, though he was famous for tearing down battlefield monuments. He had too much respect for the common soldier to damage a monument to him. Similarly, he left the monument at Vimy Ridge severely alone.
According to the Wikipedia, quote "Except for the occupation by the Germans in World War II when the daily ceremony was conducted at Brookwood Military Cemetery, in Surrey, England, this ceremony has been carried on uninterrupted since, 2 July 1928. On the very evening that Polish forces liberated Ypres in the Second War, the ceremony was resumed at the Menin Gate despite the fact that heavy fighting was still taking place in other parts of the town."
I heard a different story, but I'll leave that for now pending further research.
The stair wells, lined with names and flooded with tears from Belgian, French, British, Canadian, Indian, Australian, and South African soldiers.
Newfoundland and New Zealand soldiers have their own memorials. Lord Plumer of Messines, at the unveiling of the Menin Gate, 1927 said. . .
"One of the most tragic features of the Great War was the number of casualties reported as 'missing, believed killed'.
To their relatives there must have been added to their grief a tinge of bitterness and a feeling that everything possible had not been done to recover their loved ones' bodies and give them reverent burial ... when peace came, and the last ray of hope had been extinguished, the void seemed deeper and the outlook more forlorn.
For those who had no grave to visit, no place where they could lay tokens of loving remembrance ... and it was resolved that here at Ypres, where so many of the missing are known to have fallen, there should be erected a memorial worthy of them which should give expression to the nation's gratitude for their sacrifice and their sympathy with those who mourned them. A memorial has been erected which, in its simple grandeur, fulfils this object, and now it can be said of each one in whose honour we are assembled"
Blomfield's memorial combines the architectural images of a classical victory arch and a mausoleum and it contains, inside and out, huge panels into which are carved the names of the 54,896 officers and men of the commonwealth forces who died in the Ypres Salient area and who have no known graves. This figure, however, does not represent all of the missing from this area. It was found that the Menin Gate, immense though it is, was not large enough to hold the names of all the missing.
The names recorded on the gate's panels are those of men who died in the area between the outbreak of the war in 1914 and 15th August, 1917. The names of a further 34,984 of the missing - those who died between 16th August, 1917 and the end of the war, are recorded on carved panels at Tyne Cot Cemetery, on the slopes just below Passchendaele.
"What are you guarding, Man-at-Arms?
Why do you watch and wait?"
"I guard the graves," said the Man-at-Arms,
"I guard the graves by Flanders Farms,
Where the dead will rise at my call to arms,
And march to the Menin Gate."