Question: What historic castle, located on the north bank of the River Thames is famous for imprisoning people such as Clement Walker?

Context paragraphs:
Jubilee River: The Jubilee River is a hydraulic channel in southern England.  It is 11.6 km long and is on average 45 m wide.  It was constructed in the late 1990s and early 2000s to take overflow from the River Thames and so alleviate flooding to areas in and around the towns of Maidenhead, Windsor, and Eton in the counties of Berkshire and Buckinghamshire.  It achieves this by taking water from the left (at this point eastern) bank of the Thames upstream of Boulter's Lock near Maidenhead and returning it via the north bank downstream of Eton, Berkshire.  Although successful in its stated aims, residents of villages downstream claim it has increased flooding.

Chiswick Bridge: Chiswick Bridge is a reinforced concrete deck arch bridge over the River Thames in west London.  One of three bridges opened in 1933 as part of an ambitious scheme to relieve traffic congestion west of London, it carries the A316 road between Chiswick on the north bank of the Thames and Mortlake on the south bank.

Westminster Millennium Pier: Westminster Millennium Pier is a pier on the River Thames, in the City of Westminster in London, UK.  It is operated by London River Services and served by various river transport and cruise operators.  It is located next to Westminster Bridge on the north bank of the Thames, and is close to one of London's most promininent landmarks, Big Ben.

Vauxhall Bridge: Vauxhall Bridge is a Grade II* listed steel and granite deck arch bridge in central London.  It crosses the River Thames in a south–east north–west direction between Vauxhall on the south bank and Pimlico on the north bank.  Opened in 1906, it replaced an earlier bridge, originally known as Regent Bridge but later renamed Vauxhall Bridge, built between 1809 and 1816 as part of a scheme for redeveloping the south bank of the Thames.  The original bridge was built on the site of a former ferry.

Clement Walker: Clement Walker (died 1651) was an English lawyer, official and politician.  As a member of the Long Parliament, he became an outspoken critic of the conduct of its affairs, and allied himself to William Prynne.  Author of the "History of Independency", which as a project with several editions included also his "Anarchia Anglicana", he was a strong opponent of religious factionalism, and was imprisoned in the Tower of London, where he died without being brought to trial.  He used the pseudonym Theodorus Verax.

River Tyburn: The River Tyburn is a river in London, which runs underground from South Hampstead through St James's Park to meet the River Thames by Whitehall Stairs (near Downing Street and Thorney Street, between Millbank Tower and Thames House).  It is not to be confused with the Tyburn Brook which is a tributary of the River Westbourne that is the next Thames tributary to the west on the north bank.

Twickenham Bridge: Twickenham Bridge crosses the River Thames in southwest London, England.  Built in 1933 as part of the newly constructed "Chertsey Arterial Road", the bridge connects the Old Deer Park district of Richmond (historically Surrey) on the south bank of the river to St. Margarets (historically Middlesex) on the north bank, both within the London Borough of Richmond upon Thames.  Twickenham Bridge gets its name from the fact that it is on the road to the town of Twickenham (also in the same London borough), which is approximately 3 km upstream from Twickenham Bridge, past Richmond Bridge.

Millbank Distillery: Millbank Distillery was a London gin distillery owned and operated by Seager Evans and Co..  It was located on Grosvenor Road on the North bank of the River Thames in Pimlico.  The company's best known product, Seagers Gin, was produced here up until the early 20th century.  Millbank Distillery is often confused with Thames Bank Distillery a slightly older distillery, founded in 1797 and located further west along the river.  Thames Bank Distillery was owned by Octavius Smith & Company - it was located on Grosvenor Road - its rear boundary was Lupus Street and on either side of it were Glasgow Terrace and Turpentine Lane.

Tower of London: The Tower of London, officially Her Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle located on the north bank of the River Thames in central London.  It lies within the London Borough of Tower Hamlets, separated from the eastern edge of the square mile of the City of London by the open space known as Tower Hill.  It was founded towards the end of 1066 as part of the Norman Conquest of England.  The White Tower, which gives the entire castle its name, was built by William the Conqueror in 1078 and was a resented symbol of oppression, inflicted upon London by the new ruling elite.  The castle was used as a prison from 1100 (Ranulf Flambard) until 1952 (Kray twins), although that was not its primary purpose.  A grand palace early in its history, it served as a royal residence.  As a whole, the Tower is a complex of several buildings set within two concentric rings of defensive walls and a moat.  There were several phases of expansion, mainly under Kings Richard the Lionheart, Henry III, and Edward I in the 12th and 13th centuries.  The general layout established by the late 13th century remains despite later activity on the site.

Savoy Place: Savoy Place is a large red brick building on the north bank of the River Thames in London.  It is on a street called Savoy Place and Savoy Street runs along the side of the building up to the Strand.  In front is the Victoria Embankment, part of the Thames Embankment.  Close by are Savoy Hill House (best known for accommodating the BBC Savoy Hill recording studios), the Savoy Hotel and Waterloo Bridge.  There are commanding views over to the South Bank and the London Eye.

Supporting paragraphs: Clement Walker Tower of London
Answer: Tower of London