Where the facts come from
Every factual claim on this site links to its source. This is the full list.
How we checked
Each fact was written alongside its source. Our build script stores the source text and, for every fact, checks that the key words and figures really appear in it. 203 of 203 checks passed when this site was last built (checked 3 Nov 2026). Where we couldn’t read a source, we left the claim out. We quote short phrases only, and never reproduce anyone’s photographs or plans.
Figures that change
Entry, access and what a place is used for today can change. Facts like these are marked “checked 3 Nov 2026”.
What we leave out
This is a site about the history of star forts and about spotting and visiting them. It isn’t a visitor guide with live opening times, prices or access advice: check with the site you’re visiting. Where a source gives an interpretation or says the answer is unknown, we say so rather than choose for it.
UNESCO World Heritage Centre (2)
- UNESCO World Heritage Centre: Fortifications of Vauban (6 facts)
- UNESCO World Heritage Centre: Venetian Works of Defence between the 16th and 17th Centuries (5 facts)
Network of Vauban’s Major Sites (15)
- Network of Vauban’s Major Sites: History of the bastioned fortification (14 facts)
- Network of Vauban’s Major Sites: Vauban (15 facts)
- Network of Vauban’s Major Sites: Bastioned fortifications (5 facts)
- Network of Vauban’s Major Sites: Neuf-Brisach (8 facts)
- Network of Vauban’s Major Sites: glossary, Third system (1 fact)
- Network of Vauban’s Major Sites: glossary, Three systems (2 facts)
- Network of Vauban’s Major Sites: glossary, Bastion (3 facts)
- Network of Vauban’s Major Sites: glossary, Demi-lune or ravelin (1 fact)
- Network of Vauban’s Major Sites: glossary, Glacis (1 fact)
- Network of Vauban’s Major Sites: glossary, Curtain wall (1 fact)
- Network of Vauban’s Major Sites: glossary, Covert way (1 fact)
- Network of Vauban’s Major Sites: glossary, Citadel (1 fact)
- Network of Vauban’s Major Sites: glossary, Counterscarp (1 fact)
- Network of Vauban’s Major Sites: glossary, Embrasure (1 fact)
- Network of Vauban’s Major Sites: glossary, Parapet (1 fact)
English Heritage and Historic England (5)
- English Heritage: History of Tilbury Fort (14 facts)
- English Heritage: Tilbury Fort (4 facts)
- Historic England: Tilbury Fort, list entry 1021092 (3 facts)
- English Heritage: History of Berwick-upon-Tweed Castle and Ramparts (13 facts)
- English Heritage: Berwick-upon-Tweed Castle and Ramparts (3 facts)
Historic Environment Scotland (3)
- Historic Environment Scotland: Fort George, history (9 facts)
- Historic Environment Scotland: Fort George (5 facts)
- Historic Environment Scotland: Fort Charlotte, history (5 facts)
US National Park Service (7)
- US National Park Service: The Star Fort (Fort McHenry) (4 facts)
- US National Park Service: History of Fort McHenry (8 facts)
- US National Park Service: The Bombardment of Fort McHenry, part 1 (3 facts)
- US National Park Service: Castillo de San Marcos National Monument (1 fact)
- US National Park Service: Castillo de San Marcos, construction (8 facts)
- US National Park Service: Castillo de San Marcos (article) (6 facts)
- US National Park Service: Coquina, the rock that saved St Augustine (4 facts)
Japan National Tourism Organization and Visit Hokkaido (2)
- Japan National Tourism Organization: Goryokaku Fort (5 facts)
- Visit Hokkaido: Goryokaku Fort (7 facts)
Fortress Bourtange and Visit Groningen (2)
- Fortress Bourtange: History of Bourtange (11 facts)
- Visit Groningen: Fort Bourtange (2 facts)
Visit Palmanova and italia.it (2)
- Visit Palmanova: The Fortress City (10 facts)
- italia.it: Palmanova (4 facts)
GOV.UK (Department for Education) (1)
- Department for Education: National curriculum in England, history programmes of study (GOV.UK) (7 facts)
When sources disagree
Where sources give different dates, or say something is an interpretation or unknown, we show all of it, with links, and say how we handle it.
When and where did the bastion begin?
- After metal cannonballs came into general use at the end of the 15th century, Italian engineers designed a new kind of defence: the bastioned system. Network of Vauban’s Major Sites: History of the bastioned fortification
- The National Park Service says the star-shaped bastion design originated in Italy in the 15th century. US National Park Service: Castillo de San Marcos, construction
- Bastioned fortification was introduced and developed first by Italian and then Dutch engineers from the 16th century onwards. Network of Vauban’s Major Sites: Bastioned fortifications
- Another National Park Service page says the bastion system was developed by Italians in the 17th century. US National Park Service: Castillo de San Marcos (article)
- English Heritage says bastioned fortification was found first in Italy, at Verona. English Heritage: History of Berwick-upon-Tweed Castle and Ramparts
- UNESCO calls the territory of the Republic of Venice “the near-exclusive setting of the genesis of the alla moderna or bastioned system” during the Renaissance. UNESCO World Heritage Centre: Venetian Works of Defence between the 16th and 17th Centuries
How we handle it: Every source here points to Italy, but they give different centuries: the end of the 15th, the 15th, from the 16th onwards, and the 17th. One names Verona; UNESCO names the lands of the Republic of Venice. We quote each one.
When was Fort McHenry built?
- One NPS page says Fort McHenry was built between 1799 and 1802. US National Park Service: The Star Fort (Fort McHenry)
- Another NPS page says building began in 1798 and the fort was completed in 1803. US National Park Service: History of Fort McHenry
How we handle it: Two National Park Service pages give different years: 1799 to 1802, and 1798 to 1803.
How thick are the Castillo’s walls?
- One NPS page gives the walls as 14 feet thick. US National Park Service: Castillo de San Marcos (article)
- Another NPS page says the walls average 12 feet (3.7 m) thick, and up to 19 feet (5.8 m) on the ocean side. US National Park Service: Coquina, the rock that saved St Augustine
How we handle it: One National Park Service page says 14 feet; another says an average of 12 feet, and up to 19 feet on the ocean side.
How long did the Castillo hold out?
- During an English siege the Castillo once sheltered over 1,500 people for 51 days. US National Park Service: Castillo de San Marcos, construction
- In 1740 General Oglethorpe bombarded the Castillo for 27 days, and the walls held. US National Park Service: Coquina, the rock that saved St Augustine
How we handle it: One page says it sheltered over 1,500 people for 51 days during an English siege; another says Oglethorpe bombarded it for 27 days in 1740. The first page gives no year, so from these pages we cannot tell if both describe the same siege.
1868 or 1869 at Goryokaku?
- The Japan National Tourism Organization says the final battle of the Boshin War was fought at Goryokaku in 1869. Japan National Tourism Organization: Goryokaku Fort
- Visit Hokkaido calls it the 1868 Battle of Hakodate. Visit Hokkaido: Goryokaku Fort
- Visit Hokkaido says the text on its Goryokaku page includes machine translations. Visit Hokkaido: Goryokaku Fort
How we handle it: The Japan National Tourism Organization dates the final battle to 1869; Visit Hokkaido calls it the 1868 Battle of Hakodate, and says its page includes machine translations.
When did Bourtange begin?
- In 1580 William of Orange ordered a fort with five bastions to be built on a sandy ridge in the Bourtange marsh. Fortress Bourtange: History of Bourtange
- Visit Groningen says William of Orange commissioned the first fortification at Bourtange in 1580. Visit Groningen: Fort Bourtange
- Fortress Bourtange says the fortress was erected in 1593, commissioned by William Louis of Nassau. Fortress Bourtange: History of Bourtange
How we handle it: Fortress Bourtange gives both 1580, when William of Orange ordered the fort, and 1593, when it says the fortress was erected. Visit Groningen gives 1580.
Who built Palmanova’s third ring of walls?
- Palmanova has three rings of walls: two built by Venice, with nine bastions and nine ravelins, and an outer ring of nine “lunettes” added by Napoleon in the early 19th century. Visit Palmanova: The Fortress City
- italia.it says the third ring was built in 1805 by the French. italia.it: Palmanova
How we handle it: Palmanova’s own site says Napoleon added it in the early 19th century; italia.it says the French built it in 1805. These fit together, but they are worded differently.
Did Vauban have “three systems”?
- Vauban’s ideas were only described as “three systems” after his death; for him, fitting the land, common sense and experience were what counted. Network of Vauban’s Major Sites: History of the bastioned fortification
- Neuf-Brisach is the only example of Vauban’s “third system”. Network of Vauban’s Major Sites: glossary, Third system
How we handle it: The same network of sites says the three systems were only described after his death, and calls Neuf-Brisach the only example of the third system.
The best, the finest, the most complete?
- English Heritage calls Tilbury England’s best example of a 17th-century bastioned fortress. English Heritage: Tilbury Fort
- Historic Environment Scotland calls Fort George the finest example of 18th-century military engineering anywhere in the British Isles. Historic Environment Scotland: Fort George, history
- English Heritage calls Berwick’s defences the most complete bastioned town defences in England. English Heritage: Berwick-upon-Tweed Castle and Ramparts
How we handle it: These are judgements by the organisations that publish them, and each one measures something different.