Crownhill Fort Crownhill Fort is a Royal Commission Fort built in the 1860s in Crownhill as part of Lord Palmerston ' s ring of land defences for Plymouth . Restored by the Landmark Trust , it is now home to several small businesses , a wedding and events venue and a holiday apartment sleeping up to eight people . The Fort is open to the public on the last Friday of each month and hosts tours for local schools and societies at other times . History of the fort . Crownhill Fort was designed by Captain E . F . Du Cane as one of Lord Palmerston ' s last forts and was the largest of the forts of Plymouth ' s North Eastern defences , whose purpose was to defend the Royal Dockyard at Devonport from the possibility of a French attack , under the leadership of Napoleon III . Construction began in April 1863 , with Crownhill Fort being at the cutting edge of fortress design , although it does conform to the standard polygonal design of its contemporaries . It was built 400 metres in front of the defensive line , now incorporated in to the east - west Crownhill Road , in an exposed position on a natural limestone outcrop . Crownhill Fort is designed for all round defence , with each of its seven sides having massive ramparts and being surrounded by a deep ditch . All sides were also protected by gunfire , with the fort having around 350 built - in rifle loopholes . It was designed for an armament of 32 guns on the ramparts and 6 mortar s sited in two mortar pits to the south west and north west of the Parade Ground . A year later , in 1864 , Russia n commander General Todleben was shown the building works , and he complimented them . In 1866 , after a strike , George Baker , the building contractor , went bankrupt and so the work was finished by the Royal Engineers who would become Crownhill Fort ' s first occupants . The total cost of the construction was £76 , 409 ; a large sum at the time , but much less costly than other Palmerston forts . In 1881 , the Director of Artillery and Stores recommended that two forts , Fort Widley in Portsmouth and Crownhill Fort , be armed with complete peacetime armaments . None of the original armament survives but The Landmark Trust has reinstated several artillery pieces similar to those that would have occupied Forts of this kind . Due to continual advancement in weaponry and warfare many Victorian Forts were abandoned by the army . Crownhill Fort remained an MOD site until 1986 and was instead used by many different infantry regiments as HQ Plymouth Garrison . In the First World War , Crownhill Fort was used as a recruitment and transport centre for troops being sent to the fronts in Turkey and Africa . It was then used as a de - mobilisation depot before becoming a base for the newly created Royal Signals Corps . The last time Crownhill Fort was actively used in a military situation was during the Second World War , when anti - aircraft guns were positioned in the fort . Following the war , in the 1950s , it had a Gun Operations Room built on the parade ground , incorporating part of the Officers barrack . It then continued as a home for the 59 Independent Commando Squadron Royal Engineers until 1983 , despatching 647 troops and 1 , 897 tonnes of war material during the Falklands War . The fort was purchased 3 years later by the Landmark Trust who have restored Crownhill Fort to be the best preserved example of Palmerston ' s forts . In completing this task , Landmark Trust have received much assistance from grant aid courtesy of the European Committee , English Heritage and the Heritage Lottery Fund . Structure of Crownhill Fort . The basic shape of Crownhill Fort is a heptagon , incorporating many advanced Victorian fort design ideas . The Ditch . The fort is surrounded by a dry ditch , defended by caponier s , which is hewn from solid rock . 200 000 tonnes of material had to be moved to create the ditch , which is 30 ft deep and 30 ft wide . The Caponiers . Crownhill Fort has six three - storey caponiers . The first floor was for infantrymen , the second was for gun casements each housing Smooth - Bore Breech - Loading guns and the third connects with the " Chemin de Ronde " , the parapeted walkway circling the fort . The north caponier is a full caponier because it points in two directions . The other five caponiers are demi - caponiers because they face in one direction only . Crownhill Fort ' s guns . Crownhill Fort is famous for its collection of artillery . The cannon are maintained in working order and are fired on event days to recreate the sounds and atmosphere of a working fortress . In total , the fort has emplacements for 32 guns on its ramparts ( including 5 Haxo casements and 2 Moncrieff pits ) and 15 in its caponiers . Some of the guns that can be found at Crownhill Fort include : The Fort Today . Today Crownhill Fort is home to several small businesses , a holiday apartment , a wedding and events venue as well as underground tunnels , recreated Victorian and World War II barrack rooms , and a detention room . The Fort is open to the public every last Friday of every month [ www . crownhillfort . co . uk ] , with tours of the grounds bookable on request at most other times . The Fort is licensed for civil ceremonies and hosts an array of wedding receptions , private events and corporate events all year . The events are managed by Emotive Events Ltd ( parent company of leading London wedding planners Wedding Matters ) . In the past few years The Landmark Trust has been able to carry out various improvement works at the Fort .