A wooden arch for a wedding
When Napoleon married Marie-Louise in 1810, the arch had barely started. A full-size mock-up in wood and painted canvas was put up so the wedding procession could pass under it.
Napoleon ordered the arch after Austerlitz in 1806 and never saw it finished. Today the Unknown Soldier lies beneath it, and a flame is rekindled there every evening. Here's what you're looking at, and what to listen for when you get there.

When Napoleon married Marie-Louise in 1810, the arch had barely started. A full-size mock-up in wood and painted canvas was put up so the wedding procession could pass under it.
The inner walls carry the names of 128 battles and 660 officers of the Revolution and the Empire, most of them generals. Names that are underlined belong to men who died in battle.
The Unknown Soldier from the First World War was buried under the arch in 1921. Since 1923 veterans' associations have rekindled the flame every evening at 6.30 pm, without missing a day, even during the German occupation.
Napoleon ordered it in 1806; it was designed by Jean Chalgrin and finished in 1836 under King Louis-Philippe.
The Tomb of the Unknown Soldier from the First World War, with an eternal flame rekindled every evening at 6.30 pm.
Yes, there's a terrace at the top reached by 284 steps, with a ticket.