01/24/2026 Haunted Locations: Castillo de San Marcos in St. Augustine, Florida
- Danielle Yvonne
- 4 days ago
- 5 min read
Happy Saturday! Today, we take a look at Castillo de San Marcos in St. Augustine, Florida. There's a lot of history with this one, so let's skip any kind of lengthy intro and get right into it!
Castillo de San Marcos has witnessed almost 400 years of warfare, imprisonment, death, and disaster. It has been the shelter for Spanish Conquistadors, the prison for British soldiers, has housed Confederate troops, and was used as a military prison during other times of conflict and warfare. Then there’s the material alone that it was made from. The combination of all these factors, plus more, is the perfect recipe for a haunted location! So, let’s start from the beginning and break it all down!
Castillo de San Marcos is in St. Augustine, Florida. It is the oldest masonry fort in the United States. It took over 20 years to build, between 1672 and 1695. During those years, many lives were lost, including Spanish soldiers and Native Americans. Their deaths were attributed to diseases, along with both accidents and attacks that occurred during the construction.
Construction began under Spanish colonial governor Manuel de Cendoya. The fort replaced wooden stockades that pirates and enemy forces frequently overtook. Because of its strategic position at the entrance to St. Augustine’s harbor, the fort played a central role in enabling Spanish control over Florida and the important shipping routes to the Caribbean.
Castillo de San Marcos was built from Coquina, which is a rare type of limestone. This material is so thick that when an attack happened, the cannons simply bounced right off the walls. There are only two forts in the world built of this material. The walls ranged from 12 to 19 feet thick, and a large courtyard was available for people to take refuge in.
It was only 7 years after construction was completed that Queen Anne’s War began. During the war, the fort stood strong during a diabolical 58-day siege by the British. Many Spanish soldiers died due to their refusal to surrender. Many British soldiers ultimately died as well after the fort’s dungeons were used as a prison. The British then gained control over Florida in 1763. The fort was renamed Fort St. Marks and was part of the British military force. Then Spain regained it in 1783.
During the Second Seminole War, which was from 1835 until 1842, the fort was home to captured Seminole leaders. One was the famous Chief Osceola. He died in his cell under mysterious circumstances in 1838. Then, when the Civil War took place, it brought even more death to the location because the fort served as a Union prison for Confederate soldiers.
Per ghostcitytours.com, “throughout its operational period, the fort's isolation, harsh conditions, and constant threat of violence created an environment where death was commonplace and spiritual unrest inevitable.”
Okay, now that we have the bulk of the history down. It’s time to get into the spookiness of it all!
During my research, I came across an explanation on ghostsandgravestones.com that perfectly captured what I was trying to express. They articulated it far better than I could, especially touching upon the coquina material used to build the fort, so I’m quoting them directly...
"To better understand the Castillo de San Marcos, it’s essential to appreciate its layered history. Built in 1672 by the Spanish to defend their Florida territories, the fort has seen countless battles, cultural exchanges, and human tragedies. Its construction from coquina, a shell limestone material, is not just a marvel of engineering but also an element believed by some to retain the energy of the past, amplifying its paranormal activity."
There is a TON of spirits that occupy the fort and MANY paranormal encounters that have taken place at Castillo de San Marcos. One of the most notable is Captain Domingo Martinez, who was a Spanish officer and died in 1702 during the British siege while he was defending the fort. People consistently report his solid apparition on the gun deck wearing his Spanish colonial uniform. I make note that his appearance is often solid because many people, including park rangers, have documented that they’ve tried speaking to him only to realize it’s a ghost. Allegedly, the scent of gunpowder and leather accompanies him.
I mentioned above the death of Osceola, the Seminole chief who died in his cell in 1838. People report seeing his ghost right by the cell where he was being held captive. It is said that he communicates by sharing visions of the suffering he and his people endured, along with his own betrayal by the U.S. military, rather than using words/disembodied voices.
The dungeon has a bunch of different activities that are reported. It housed many British and Confederate prisoners who died while in captivity, so there is no shortage of cold spots, voices, and chains rattling when you’re down there. Per ghostcitytours.com, “Perhaps most disturbing is the collective entity known as 'The Lost Company'—a group of Spanish soldiers who were accidentally sealed in a storage room during construction in 1784 and discovered decades later as skeletons still clutching their weapons. Their collective spirit manifests as the sound of multiple footsteps marching in formation through the fort's corridors, particularly during the pre-dawn hours when they conducted their original patrol duties.”
It is said that paranormal activity really ramps up after sunset. It should also be noted that the fort has an acoustic property which is designed to amplify sound for military purposes; it seems to amplify paranormal audio. Temperature changes are also common. Thanks to ghostcitytours.com again for detailing the following about what takes place during storms at Castillo de San Marcos: “During thunderstorms, the fort becomes extraordinarily active, with witnesses reporting the sounds of battle, phantom cannon fire that seems to respond to actual thunder, and the appearance of entire ghostly military units conducting siege preparations. The most compelling evidence comes from the fort's security cameras, which regularly capture footage of figures in period military dress moving through areas that are closed to the public during overnight hours.”
I’ll be honest, when I started researching the history of this location, along with all of the paranormal activity, it was overwhelming. I could probably write a novel on all the happenings that take place at Castillo de San Marcos, but today I decided to stick with the most notable stuff. I highly encourage people who are even slightly interested to take a deep dive, because this location in general is extremely interesting and holds a ton of history. It is definitely somewhere I would love to visit.
So, tell me. Have you heard of this location before? Have you been there? Would you go? Let me know in the comments. And as always, if you do decide to visit here or any haunted location, respect the property, respect the owners, respect the residents... living or dead.
For more details about this story, how you can visit, and links to the shows, podcasts, documentaries, and resources used for this post can all be found below.
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