The Cenotaph, London

Standing beside the Cenotaph, it's hard not to feel the gravity of what this stone structure represents. It was World War I, from 1914 to 1918, that first made a monument like this necessary.

Britain entered the war on August 4, 1914, after Germany invaded Belgium. A longstanding treaty required Britain to protect Belgian neutrality, and so the declaration came. Millions of men volunteered in those early weeks, swept up in patriotism, many of them having no idea what trench warfare on the Western Front actually looked like.

The war changed Britain from the inside out. Women entered factories and offices in numbers never seen before, keeping the country running while men were at the front. By 1918, this shift was officially acknowledged when the Representation of the People Act gave women over 30 the right to vote, a landmark moment in British democracy.

When the armistice was signed on November 11, 1918, Britain had won, but the cost was staggering. The Cenotaph, meaning "empty tomb" in Greek, was built to hold all that grief in one place. Given how much happened, it seems almost modest for what it carries.