Musée de l'Armée

Listen to the gravel first. It crunches under your shoes as you cross the great courtyard, and the sound comes back off the stone arcades on every side. Above you, a dome covered in gold catches the light over the rooftops of Paris. Around you, rows of old bronze cannons point their mouths toward the sky. This is the Hôtel des Invalides, and inside its walls is the Musée de l'Armée, France's national army museum.

Before it was a museum, this place was a promise. In the 1670s, King Louis the Fourteenth ordered a vast home for wounded and elderly soldiers. Many of them had fought in his long wars, and too many ended their lives begging in the streets. The king wanted a place where they could live, eat, pray and be cared for. The building you see grew from that idea. The design of the main complex is credited to the architect Libéral Bruant.

Here is the first thing many visitors miss. The Invalides never stopped doing its original job. Part of the complex still houses a national institution that cares for injured and disabled veterans. So while tourists walk through the galleries, former soldiers still live and receive treatment behind some of these same walls. It is a working home, not only a monument.

Now look around the courtyard itself, the Cour d'honneur. This is the ceremonial heart of the Invalides. The long, two-storey arcades once gave the old soldiers sheltered walkways in rain and sun. Today, the courtyard still hosts military ceremonies and official tributes. The cannons lined up along the edges come from many periods. Some are richly decorated, with handles cast in the shape of dolphins or other animals.

Raise your eyes to the roofline and the small dormer windows. Each one carries carved military trophies — helmets, shields, armour, weapons. Locals and guides like to tell a story about one of them. According to the popular tale, one dormer shows a wolf with its paws on the window. In French, wolf is "loup", and the carving is said to be a play on the name of Louvois, the minister of war who oversaw the project — "Louvois sees". It is a charming joke, whether or not it is true. See if you can find it.

The museum itself was created in 1905. Two earlier collections came together — an artillery museum and a historical army museum. The result is one of the largest military collections in the world. It covers many centuries, from medieval armour to the two world wars of the twentieth century. You could spend an entire day here and still leave rooms unseen.

The armour galleries are a good place to begin. Here you walk among suits of plate steel made for knights, kings and their horses. Some were made for battle. Others were made mainly for display and tournaments, with engraved and gilded surfaces. Look closely at the joints at the elbows and knees. The overlapping plates allowed the wearer to bend and move. These were not clumsy metal boxes. They were precise, fitted pieces of engineering.

The Napoleonic rooms draw many visitors. Napoleon Bonaparte is everywhere in this building, in one form or another. In the collections you can see objects linked to the emperor — uniforms, weapons and personal belongings. Among the best-known items are one of his famous two-cornered hats, the bicorne, and his grey overcoat. Even his horse, Vizir, has survived here, preserved and displayed. It is a strange and very personal connection to a man usually seen only in paintings.

The twentieth-century galleries change the mood. They cover the First and Second World Wars, through uniforms, maps, weapons, posters and letters. The tone here is quieter and heavier. These rooms tell the story of mass conflict, occupation and liberation. Nearby, the Invalides also holds a space dedicated to Charles de Gaulle, the leader of Free France during the Second World War. It tells his story through images, film and sound.

At the southern end of the complex rises the golden dome. It crowns a church designed by Jules Hardouin-Mansart, and it was finished in the early eighteenth century. The gold you see is real gold leaf. It has been renewed several times over the centuries. One notable regilding took place in 1989, for the two hundredth anniversary of the French Revolution. On a clear day, the dome shines across much of the city.

Under that dome lies Napoleon. He died in exile on the island of Saint Helena in 1821. Nearly twenty years later, in 1840, the French government brought his remains back to Paris. A huge crowd watched the procession. His tomb was completed some years later. It is a massive sarcophagus of dark red stone, set inside an open circular crypt. You do not look up at it. You look down on it, from a balcony around the opening.

Here is the second surprise. Napoleon is not alone. Several members of his family rest in this church, and so do some of France's great military leaders. And the Invalides has two churches, joined back to back. The dome church was for the king and for ceremony. The other, the soldiers' church of Saint Louis, was for the residents of the home. Inside it, old flags captured in battle hang high along the walls.

When you leave, walk out toward the long green lawns of the esplanade in front of the main gate. Turn around once more. The whole façade stretches out before you, wide and calm. Beyond the lawns, the line of sight runs north toward the river and the Alexandre the Third bridge. Behind you are centuries of war, glory and loss. In front of you, people are walking dogs, eating lunch on the grass and talking in the sun. Take a moment to stand between the two.