Plan of the Tower of London
The Tower was orientated with its strongest and most impressive defences overlooking
Saxon London, which archaeologist
Alan Vince suggests was deliberate.
 It would have visually dominated the surrounding area and stood out to traffic on the River Thames.
 The castle is made up of three "
wards", or enclosures. The innermost ward contains the White Tower and is the earliest phase of the castle. Encircling it to the north, east, and west is the inner ward, built during the reign of
Richard the Lionheart (1189–1199). Finally, there is the outer ward which encompasses the castle and was built under
Edward I. Although there were several phases of expansion after William the Conqueror founded the Tower of London, the general layout has remained the same since Edward I completed his rebuild in 1285. The castle encloses an area of almost 12 acres (4.9 hectares) with a further 6 acres (2.4 ha) around the Tower of London constituting the
Tower Liberties – land under the direct influence of the castle and cleared for military reasons.
 The precursor of the Liberties was laid out in the 13th century when
Henry III ordered that a strip of land adjacent to the castle be kept clear.
 Despite popular fiction, the Tower of London never had a permanent torture chamber, although the basement of the White Tower housed a
rack in later periods.
Wharf was built on the bank of the Thames under Edward I and was expanded to its current size during the reign of
Richard II (1377–1399).
The White Tower is a
keep (also known as a
donjon), which was often the strongest structure in a medieval castle, and contained lodgings suitable for the lord – in this case the king or his representative.
 According to military historian Allen Brown, "The great tower [White Tower] was also, by virtue of its strength, majesty and lordly accommodation, the donjon par excellence".
 As one of the largest keeps in the
 the White Tower has been described as "the most complete eleventh-century palace in Europe".
The original entrance to the White Tower was at first-floor level
The White Tower, not including its projecting corner towers, measures 36 by 32 metres (118 by 105 ft) at the base, and is 27 m (90 ft) high at the southern battlements. The structure was originally three storeys high, comprising a basement floor, an entrance level, and an upper floor. The entrance, as is usual in
Norman keeps, was above ground, in this case on the south face, and accessed via a wooden staircase which could be removed in the event of an attack. It was probably during
Henry II's reign (1154–1189) that a forebuilding was added to the south side of the tower to provide extra defences to the entrance, but it has not survived. Each floor was divided into three chambers, the largest in the west, a smaller room in the north-east, and the chapel taking up the entrance and upper floors of the south-east.
 At the western corners of the building are square towers, while to the north-east a round tower houses a spiral staircase. At the south-east corner there is a larger semi-circular projection which accommodates the
apse of the chapel. As the building was intended to be a comfortable residence as well as a stronghold, latrines were built into the walls, and four fireplaces provided warmth.
The main building material is
rag-stone, although some local
mudstone was also used.
Caen stone was imported from northern France to provide details in the Tower's facing, although little of the original material survives as it was replaced with
Portland stone in the 17th and 18th centuries. As most of the Tower's windows were enlarged in the 18th century, only two original – albeit restored – examples remain, in the south wall at the gallery level.
The tower was terraced into the side of a mound, so the northern side of the basement is partially below ground level.
 As was typical of most keeps,
 the bottom floor was an
undercroft used for storage. One of the rooms contained a well. Although the layout has remained the same since the tower's construction, the interior of the basement dates mostly from the 18th century when the floor was lowered and the pre-existing timber
vaults were replaced with brick counterparts.
 The basement is lit through small slits.
St John's Chapel, inside the White Tower
The entrance floor was probably intended for the use of the
Constable of the Tower,
Lieutenant of the Tower of London and other important officials. The south entrance was blocked during the 17th century, and not reopened until 1973. Those heading to the upper floor had to pass through a smaller chamber to the east, also connected to the entrance floor. The
St John's Chapel occupied the south-east corner and was accessible only from the eastern chamber. There is a recess in the north wall of the crypt; according to Geoffrey Parnell, Keeper of the Tower History at the Royal Armouries, "the windowless form and restricted access, suggest that it was designed as a strong-room for safekeeping of royal treasures and important documents".
The upper floor contained a grand hall in the west and residential chamber in the east – both originally open to the roof and surrounded by a gallery built into the wall – and St John's Chapel in the south-east. The top floor was added in the 15th century, along with the present roof.
 St John's Chapel was not part of the White Tower's original design, as the apsidal projection was built after the basement walls.
 Due to changes in function and design since the tower's construction, except for the chapel little is left of the original interior.
 The chapel's current bare and unadorned appearance is reminiscent of how it would have been in the Norman period. In the 13th century, during Henry III's reign, the chapel was decorated with such ornamentation as a gold-painted cross, and
stained glass windows that depicted the
Virgin Mary and the
The innermost ward encloses an area immediately south of the White Tower, stretching to what was once the edge of the River Thames. As was the case at other castles, such as the 11th-century
Hen Domen, the innermost ward was probably filled with timber buildings from the Tower's foundation. Exactly when the royal lodgings began to encroach from the White Tower into the innermost ward is uncertain, although it had happened by the 1170s.
 The lodgings were renovated and elaborated during the 1220s and 1230s, becoming comparable with other palatial residences such as
 Construction of Wakefield and Lanthorn Towers – located at the corners of the innermost ward's wall along the river – began around 1220.
[nb 1] They probably served as private residences for the queen and king respectively. The earliest evidence for how the royal chambers were decorated comes from Henry III's reign: the queen's chamber was whitewashed, and painted with flowers and imitation stonework. A
great hall existed in the south of the ward, between the two towers.
 It was similar to, although slightly smaller than, that also built by Henry III at
 Near Wakefield Tower was a
postern gate which allowed private access to the king's apartments. The innermost ward was originally surrounded by a protective ditch, which had been filled in by the 1220s. Around this time, a kitchen was built in the ward.
 Between 1666 and 1676, the innermost ward was transformed and the palace buildings removed.
 The area around the White Tower was cleared so that anyone approaching would have to cross open ground. The Jewel House was demolished, and the
Crown Jewels moved to Martin Tower.
The inner ward was created during Richard the Lionheart's reign, when a moat was dug to the west of the innermost ward, effectively doubling the castle's size.
 Henry III created the ward's east and north walls, and the ward's dimensions remain to this day.
 Most of Henry's work survives, and only two of the nine towers he constructed have been completely rebuilt.
 Between the Wakefield and Lanthorn Towers, the innermost ward's wall also serves as a
curtain wall for the inner ward.
 The main entrance to the inner ward would have been through a
gatehouse, most likely in the west wall on the site of what is now Beauchamp Tower. The inner ward's western curtain wall was rebuilt by Edward I.
 The 13th-century Beauchamp Tower marks the first large-scale use of brick as a building material in Britain, since the 5th-century departure of the Romans.
 The Beauchamp Tower is one of 13 towers that stud the curtain wall. Anti-clockwise from the south-west corner they are: Bell, Beauchamp, Devereux, Flint, Bowyer, Brick, Martin, Constable, Broad Arrow, Salt, Lanthorn, Wakefield, and the Bloody Tower.
 While these towers provided positions from which
flanking fire could be deployed against a potential enemy, they also contained accommodation. As its name suggests, Bell Tower housed a belfry, its purpose to raise the alarm in the event of an attack. The royal bow-maker, responsible for making
catapults, and other siege and hand weapons, had a workshop in the Bowyer Tower. A turret at the top of Lanthorn Tower was used as a beacon by traffic approaching the Tower at night.
The south face of the Waterloo Block
As a result of Henry's expansion,
St Peter ad Vincula, a Norman chapel which had previously stood outside the Tower, was incorporated into the castle. Henry decorated the chapel by adding glazed windows, and stalls for himself and his queen.
 It was rebuilt by Edward I at a cost of over £300
 and again by
Henry VIII in 1519; the current building dates from this period, although the chapel was refurbished in the 19th century.
 Immediately west of Wakefield Tower, the Bloody Tower was built at the same time as the inner ward's curtain wall, and as a water-gate provided access to the castle from the River Thames. It was a simple structure, protected by a
portcullis and gate.
 The Bloody Tower acquired its name in the 16th century, as it was believed to be the site of the murder of the
Princes in the Tower.
 Between 1339 and 1341, a gatehouse was built into the curtain wall between Bell and Salt Towers.
 During the Tudor period, a range of buildings for the storage of munitions was built along the inside of the north inner ward.
 The castle buildings were remodelled during the
Stuart period, mostly under the auspices of the Office of Ordnance. In 1663 just over £4,000 was spent building a new storehouse (now known as the New Armouries) in the inner ward.
 Construction of the Grand Storehouse north of the White Tower began in 1688, on the same site as the dilapidated Tudor range of storehouses;
 it was destroyed by fire in 1841. The Waterloo Block, a former barracks in the castellated Gothic Revival style with Domestic Tudor details,
 was built on the site and remains to this day, housing the Crown Jewels on the ground floor.
A third ward was created during Edward I's extension to the Tower, as the narrow enclosure completely surrounded the castle. At the same time a
bastion known as Legge's Mount was built at the castle's north-west corner. Brass Mount, the bastion in the north-east corner, was a later addition. The three rectangular towers along the east wall 15 metres (49 ft) apart were dismantled in 1843. Although the bastions have often been ascribed to the Tudor period, there is no evidence to support this; archaeological investigations suggest that Legge's Mount dates from the reign of Edward I.
battlements (also known as crenellations) in the south side of Legge's Mount are the only surviving medieval battlements at the Tower of London (the rest are Victorian replacements).
 A new 50-metre (160 ft) moat was dug beyond the castle's new limits;
 it was originally 4.5 metres (15 ft) deeper in the middle than it is today.
 With the addition of a new curtain wall, the old main entrance to the Tower of London was obscured and made redundant; a new entrance was created in the south-west corner of the external wall circuit. The complex consisted of an inner and an outer gatehouse and a
 which became known as the Lion Tower as it was associated with the animals as part of the Royal Menagerie since at least the 1330s.
 The Lion Tower itself no longer survives.
 Edward extended the south side of the Tower of London onto land that had previously been submerged by the River Thames. In this wall, he built St Thomas's Tower between 1275 and 1279; later known as
Traitors' Gate, it replaced the Bloody Tower as the castle's water-gate. The building is unique in England, and the closest parallel is the now demolished water-gate at the
Louvre in Paris. The dock was covered with
arrowslits in case of an attack on the castle from the River; there was also a portcullis at the entrance to control who entered. There were luxurious lodgings on the first floor.
 Edward also moved the
Royal Mint into the Tower; its exact location early on is unknown, although it was probably in either the outer ward or the Lion Tower.
 By 1560, the Mint was located in a building in the outer ward near Salt Tower.
 Between 1348 and 1355, a second water-gate, Cradle Tower, was added east of St Thomas's Tower for the king's private use.