This Pennsylvania Castle Was Built by an Eccentric Archaeologist With an Unlikely Helper Named Lucy

Fonthill Castle, Pennsylvania

Most concrete buildings are boring boxes.

But in 1908, eccentric archaeologist Henry Mercer had a different idea – build a 44-room concrete castle in Pennsylvania, fill it with handmade tiles from around the world, and live there like some kind of arts and crafts mad scientist.

Welcome to Fonthill.

Mercer built his castle with clay models

Henry Mercer built Fonthill Castle without any blueprints at age 51. Instead, he made small clay models of each room, pushed them together, and created a plaster model to guide construction.

After getting money from his aunt in 1905, he started building in 1908 and finished in 1912.

You’ll notice this spontaneous design when you see the 32 staircases that often lead nowhere and 44 rooms with no right angles.

A horse named Lucy helped build it

Lucy the horse earned a daily wage just like the human workers during construction.

She ran the concrete lift system and knew exactly when to move forward and back without anyone telling her what to do.

Lucy carried all the concrete boxes up to workers on the higher levels. During your tour, you’ll hear stories about Lucy, and you might spot references to her in some of the decorative tiles throughout the castle.

You can see 4,000-year-old tablets in the walls

Some of the oldest items at Fonthill are clay tablets from Mesopotamia dating back to 2300 BCE. Mercer stuck these ancient tablets right into the concrete walls of the dining room and made special tiles to label them.

These tiny tablets were once used as receipts and are part of the 6,000 artifacts Mercer collected while traveling through Europe and Central America in the late 1800s. Many people walk right past these treasures without even noticing them.

Workers mixed all the concrete by hand

All the concrete for this 44-room castle was mixed by hand using Mercer’s special recipe. He used 1 part Portland cement, 2½ parts yellow Jersey gravel sand, and 5 parts bluish crushed stone from nearby Rockhill Station.

A team of 8-10 workers with no special training mixed this concrete without any machines or power tools. This rough, dry concrete mix has a unique texture that’s lasted for over 100 years.

Mercer proved his castle wouldn’t burn down

Mercer was so worried about fire that when the castle was done, he climbed to the highest tower and lit a huge bonfire. Everyone in Doylestown could see this demonstration proving his concrete home wouldn’t burn.

His concern came from seeing historical items destroyed by fire, including a big blaze at the Pennsylvania Museum in 1899. Thanks to his fireproof design, his collections have stayed safe for over 115 years.

You’ll sit on concrete furniture here

Throughout the castle, you’ll find furniture made of concrete built right into the structure. Mercer created concrete bookcases for his 6,000 books, concrete desks with built-in drainage for ink wells, concrete dressers, and even a concrete cabinet for 66 keys.

He made each piece to fit the castle’s odd-shaped rooms with no standard right angles. He chose concrete furniture because it wouldn’t burn, would last forever, and could be custom-made to fit anywhere.

The walls used to be bright pastel colors

When first built, Fonthill’s interior walls were painted in bright pastel colors, not the plain gray you see today. Years of sunlight through the 200+ windows has faded these colorful walls.

One room in the Terrace Pavilion (built where an old barn once stood) shows the original pastel colors. The castle once had blue, pink, green, and yellow rooms, making it much more cheerful than the gray concrete you see now.

The Saloon isn’t what you might think

The biggest room in Fonthill is called the “Saloon,” but you won’t find any drinks there. This name comes from old European castles where the saloon was a grand meeting hall.

This impressive room has a two-story ceiling with concrete columns shaped like trees with spreading branches. Mercer used this 30-by-20-foot space to show off his best tiles to potential customers.

Ceilings were made using piles of trash

Mercer created the curved ceilings using piles of weeds, hay, and garbage. Workers would heap these materials on wooden scaffolds, cover them with boxes, dirt, and sand, set tiles face-down in the sand, and pour concrete on top.

After it dried, they removed all the underlying stuff, leaving uniquely shaped ceilings with tiles embedded in them. No two rooms have the same ceiling pattern, and if you look closely, you can still see chicken wire in some ceiling areas where it held the garbage in place.

Modern heating hides behind decorative tiles

Despite looking medieval, Fonthill had modern conveniences for 1912. Mercer hid radiators behind decorative tile panels with small vents to let heat out.

The castle also had two dumbwaiters, an Otis elevator, phones between rooms, and a buzzer system. These hidden features let the castle keep its historical look while having modern comforts.

Mercer even set up special work areas in his office to catch the best natural light throughout the day.

Laura the housekeeper’s ghost still visits

Laura Swain, Mercer’s housekeeper, lived in Fonthill from Mercer’s death in 1930 until she died in 1975. Many staff and visitors say her ghost still walks the dark hallways.

People report lights turning on by themselves and footsteps in empty corridors. When Mercer died with no children, he left Fonthill as a museum but let Laura and her husband Frank live there until they died.

Laura gave tours during those 45 years, and some visitors claim they’ve met her ghost still leading tours decades after her death.

Secret passages wind through the castle

Several hidden corridors and secret rooms exist throughout Fonthill, showing Mercer’s love of mystery. Many of these passages aren’t shown on regular tours and remain largely unexplored.

You’ll find narrow, twisting staircases that sometimes lead to dead ends or surprise locations, deliberately designed to create a maze. Mercer loved Gothic literature, especially Edgar Allan Poe, whose dark style inspired many mysterious elements in the castle.

Even experienced guides sometimes get lost in the maze-like layout with its 32 different staircases.

A dog left paw prints all over the floors

Mercer’s dog Rollo left actual paw prints throughout the castle. During construction, Mercer let his Chesapeake Bay Retriever walk across wet concrete floors and stairs, permanently marking them.

A spiral staircase known as “Rollo’s Stairs” shows the clearest paw prints going up to one of the towers. These unique marks add a personal touch to the imposing building and show how much Mercer loved his pets.

You’ll see the dog prints alongside handprints and signatures from the workers who built the castle.

Fonthill was actually a giant showroom

Fonthill wasn’t just Mercer’s home—it was a clever marketing tool for his tile business. He invited rich potential customers to tour the castle to see his Moravian tiles installed in real rooms.

The fanciest tile designs appear in places where visitors spent the most time, featuring over 200 different patterns made at his factory. The castle displays about 900 different print plates Mercer designed, showing color options and ways to use them.

This smart marketing approach helped him win big jobs, including the floor of the Pennsylvania State Capitol in 1904-1905.

Visiting Fonthill Castle

Fonthill Castle is at 525 East Court Street, Doylestown, Pennsylvania. Open Tuesday through Sunday, 10:00 AM to 5:00 PM (closed Mondays).

Adults $16, Seniors $14, Youth $9. Tours run for one hour and reservations are recommended. The building has steep stairs and narrow passages.