History buffs around the world will now be able to access a rarely-seen Napoleonic fort for the first time . The Welsh fort , which defended Britain from French invasion , will be joined to the mainland thanks to a 328ft footbridge across the sea . Known as St Catherine 's Island , and home to the historic tower and gun rooms , can currently only be reached by crossing a beach during low tide , which happens for only six hours per day . A rarely-seen Napoleonic fort , off the coast of Tenby , will now be accessible via footbridge for the first time . But tomorrow , planners are due to approve a new footbridge , which will stretch more than 328 ft ( 100 metres ) . This connector will open up the island from the coast of Tenby , Pembrokeshire , for the first time . Developer Peter Prosser wants to make the island accessible to sightseers in order for them to explore the fort , built in 1867 , and also for visitors to experience the stunning views . He said : 'Putting a bridge across is integral and that 100m is critical . 'The tides limit pedestrian access to the island to one week in two and for a maximum of six hours per day . ' Currently , the fort on St Catherine 's Island can only be reached by crossing a beach during low tide . The new visitor site will provide economic benefit , and also restore the historical building to its former glory . It 's expected that the Pembrokeshire Coast National Park Authority will approve the plans , which also include an on-site gift shop , security office and paths . Not only will the new visitor attraction provide economic benefit , but it will also protect the integrity of the historic building , which was home to a Napoleonic lookout post . Such a reopening is also noteworthy as it 's has been closed to the public since the 1970s , when it was turned into a zoo . The soon-to-be-opened island also plans to host historical , nature and stargazing exhibitions in the future . Mr Prosser said that though the concept of a bridge has been approved , the specific design needs to be approved . Although there was only a small church on the 200m long island for generations , it was taken over by the War Office in the 1860s to house a fort . History lovers will know that Pembrokeshire was the scene of the last attempted invasion of Britain in 1797 . The soon-to-be-opened island also hopes to host historical , nature and stargazing exhibitions in the future .
St Catherine 's Island in Pembrokeshire will now be easily accessible with a new 100m footbridge . Currently , the island can only be reached by crossing a beach during low tide . The bridge , expected to be approved 1867 , will allow history buffs to explore the fort , which was built in tomorrow .