What Is a Lunette Window?

If you’ve spent any time gawking at old houses or wandering through European cathedrals, you’ve probably seen one without even realizing it. The graceful half-moon of glass tucked above a grand doorway. The curved opening spilling light into an otherwise dim hall. That, my friends, is a lunette window.

The term comes from the French lunette — “little moon.” And that’s exactly what it looks like: a moon-shaped slice of light. Long before “open concept” was a thing, architects were cutting crescents out of masonry to brighten up foyers, sanctuaries, and stair halls. If you’re working on a historic home, chances are good you’ll bump into one sooner or later.

From Rome to the Front Porch

The lunette isn’t some trendy Pinterest idea. It’s been around for nearly two thousand years. The Romans, masters of arches, were already working the look into their basilicas by the early 300s AD — the Basilica of Maxentius in Rome sports them in its soaring vaults.

Fast-forward to the Middle Ages and Renaissance, and these “little moons” started pulling double duty. Medieval builders tucked sculpture or stained glass into them; Renaissance architects made them a deliberate design move, balancing the heavy geometry of domes and barrel vaults with graceful curves.

By the time we hit the Baroque and Neoclassical periods, lunettes were practically a design flex. Churches used them to punctuate chapels. Palaces framed them with gilded plaster and frescoes.

Georgian and Federal architects in the young United States weren’t about to miss out either — they slapped lunettes over stately doors and along symmetrical façades, sometimes dressed up with elegant muntin patterns. Tiffany Studios even produced stained-glass lunettes with peacock feathers in the late 1800s. Talk about turning up the glamour.

Spotting Lunettes in the Wild

Today, you’ll find lunette windows in all sorts of historic styles: heavy Romanesque and Gothic stonework, Renaissance and Baroque palaces, Neoclassical mansions, Beaux-Arts courthouses, and even Victorian or Arts & Crafts homes with stained glass flair.

Anywhere there’s an arch, there’s a good chance someone decided to fill it with a lunette.

Lunette vs. Fanlight

Here’s where terminology gets slippery. Are a lunette and a fanlight the same thing? Not quite.

A fanlight is actually a type of lunette — the semi-circular window over a door with glazing bars radiating like a sunburst or a peacock’s tail. It’s the Instagram-worthy look you’ll see on elegant Federal and Georgian doorways. But not every lunette has that “fan” pattern. Some are plain panes. Some are leaded with decorative tracery. Some aren’t glazed at all and just act as a design motif.

Think of it this way: every fanlight is a lunette, but not every lunette is a fanlight. Like bourbon and whiskey, one’s a subset of the other.

Why You Should Care

If you own or work on an older home, spotting a lunette matters. These aren’t just pretty shapes:

• They’re a light hack from before electricity, pulling daylight into stair halls and foyers without giving away privacy by putting glass in the front door.
• They help with structural stability; the arch form spreads load better than a flat lintel.
• They’re a character marker, mess one up during restoration and any architecture nerd will know.

And if you’re replacing or reglazing one, details count: muntin thickness, curve accuracy, glazing type. Authenticity is everything.

The Takeaway

A lunette window is more than just a half circle of glass. It’s two millennia of architectural history — from Roman basilicas to Federal-style doorways to Tiffany’s stained-glass artistry. It’s a design move that signals elegance and technical skill. And it’s not always a fanlight (though fanlights are part of the family).

Next time you walk past an old building, look up. That “little moon” smiling above the door has seen centuries come and go — and if you’re lucky enough to restore one, treat it with the respect it deserves.