The Romans: England's Oldest Lighthouse (c. AD 50)
Before the medieval castle existed, the Romans built a lighthouse — the Pharos — on the clifftop around AD 50 to guide shipping across the strait they called the Fretum Gallicum. The Pharos still stands within the castle grounds to a height of approximately 40 feet, making it one of the tallest surviving Roman structures in Britain. A twin once stood on the Western Heights opposite; only its lower courses remain. The surviving Pharos later became the bell tower for the adjacent Saxon church of St Mary in Castro, creating one of the most remarkable accumulations of Roman, Saxon, and Norman history on a single site in England.
The Roman Pharos originally stood six storeys high. Four of those storeys survive in original Roman brick and tufa. The Romans used pink cement — still visible in the walls — made by mixing volcanic ash with lime.
William the Conqueror (1066)
Eight days after the Battle of Hastings, William the Conqueror arrived at Dover and ordered a castle to be constructed on the existing Saxon earthwork. Contemporary accounts say it was built in eight days — earth and timber rather than stone, but planted precisely where it would command the narrowest Channel crossing. Dover's logic was obvious from the start: 21 miles to France, control the crossing, control England.
Henry II and the Great Tower (1180s)
King Henry II transformed Dover from a timber fortification into England's most sophisticated royal fortress between 1181 and 1189, spending over £6,000 — several years of royal income. The Great Tower he built still dominates the site: 83 feet tall, walls up to 21 feet thick, with grand state apartments, a great hall, two chapels, and an internal water supply designed to survive a siege. Henry enclosed it within a ring of mural towers — one of the earliest concentric designs in English castle history. When he received Philip, Count of Flanders here in 1183, Dover was the most technologically advanced royal residence in northern Europe.
Thomas Becket was murdered in Canterbury Cathedral in 1170 — just 15 miles from Dover — following his long dispute with Henry II. Henry had used Dover Castle as a base for diplomatic meetings throughout the years of their conflict. Becket's shadow hangs over the whole region.
The Siege of 1216–17
Dover Castle's greatest military test came when French Prince Louis besieged it in 1216 during the First Barons' War. The constable, Hubert de Burgh, refused to surrender. The French tunnelled beneath the north gate and collapsed part of it; the garrison retreated, blocked the breach, and held on for three months until Louis withdrew in 1217. The damaged gate was completely redesigned afterward, and a new countermining tunnel was dug — now accessible as part of the medieval tunnel tour.
Henry VIII and the Tudors
Henry VIII updated Dover's defences as he built his coastal artillery network, and used the castle as the reception point for Holy Roman Emperor Charles V in 1520. Following Henry's break with Rome, England faced potential invasion from Catholic France and Spain, and Dover's gunports were expanded accordingly. The Tudor period added practical military upgrades rather than new architecture.
The Napoleonic Tunnel Network (1797–1809)
With Napoleon's army massing at Boulogne, military engineers carved a new level of tunnels into the chalk beneath the castle between 1797 and 1809. They could accommodate up to 2,000 troops, protected from artillery fire and ready to respond to any Channel landing. Napoleon never invaded — but the tunnels' existence would prove critical 130 years later.
Operation Dynamo: The Miracle of Dunkirk (1940)
In May and June 1940, the Napoleonic tunnels became the nerve centre of history's most audacious military rescue. Vice-Admiral Bertram Ramsay established his headquarters in the cliff tunnels and from there directed Operation Dynamo — the evacuation of 338,226 British and Allied troops from the beaches at Dunkirk over nine days.
Ramsay coordinated 850 vessels ranging from Royal Navy destroyers to Thames pleasure boats and fishing craft. He watched the evacuation from a window cut into the cliff face overlooking the harbour. Churchill called it a "miracle of deliverance." The tunnels at Dover made it possible.
Today you can walk through the same Operations Room, see the communications equipment, and follow the story of those nine days in the Secret Wartime Tunnels — included in all Dover Castle tours and tickets.
Allow at least 45 minutes for the Secret Wartime Tunnels guided tour — it runs on a set schedule. Arrive early and check the timetable at the main entrance. Book a guided Dover Castle tour from London to ensure you have enough time underground.
The Cold War
The tunnels were extended again in the Cold War as a Regional Seat of Government — one of the bunkers from which Britain would have been governed following a nuclear attack. This remained classified for decades. The Cold War layer of Dover's history was only revealed publicly in the 1980s and is now part of the tunnel experience.
Dover Castle Today
Managed by English Heritage, Dover Castle is one of England's most visited heritage sites. The Great Tower has been restored in vivid medieval colours with hologram recreations of Henry II and his court. The new Dover Castle Under Siege exhibition tells the story of the 1216 siege through immersive interactive displays. The Roman Pharos and St Mary in Castro remain in active use. See our Visitor Information page for hours and tickets.