Question: In what year were the stones at Stonehenge roped off?
About the article "Stonehenge", section "Setting and access".

Candidate passages:
  Stones at Stonehenge are fenced off.  
When Stonehenge was first opened to the public it was possible to walk among and even climb on the stones, but the stones were roped off in 1977 as a result of serious erosion.
Visitors are no longer permitted to touch the stones, but are able to walk around the monument from a short distance away.
English Heritage does, however, permit access during the summer and winter solstice, and the spring and autumn equinox.
Additionally, visitors can make special bookings to access the stones throughout the year.
The access situation and the proximity of the two roads has drawn widespread criticism, highlighted by a 2006 National Geographic survey.
In the survey of conditions at 94 leading World Heritage Sites, 400 conservation and tourism experts ranked Stonehenge 75th in the list of destinations, declaring it to be "in moderate trouble".
As motorised traffic increased, the setting of the monument began to be affected by the proximity of the two roads on either side – the A344 to Shrewton on the north side, and the A303 to Winterbourne Stoke to the south.
Plans to upgrade the A303 and close the A344 to restore the vista from the stones have been considered since the monument became a World Heritage Site.
However, the controversy surrounding expensive re-routing of the roads has led to the scheme being cancelled on multiple occasions.
On 6 December 2007, it was announced that extensive plans to build Stonehenge road tunnel under the landscape and create a permanent visitors' centre had been cancelled.
On 13 May 2009, the government gave approval for a £25 million scheme to create a smaller visitors' centre and close the A344, although this was dependent on funding and local authority planning consent.
On 20 January 2010 Wiltshire Council granted planning permission for a centre to the west and English Heritage confirmed that funds to build it would be available, supported by a £10m grant from the Heritage Lottery Fund.
On 23 June 2013 the A344 was closed to begin the work of removing the section of road and grassing it over.
The centre, designed by Denton Corker Marshall, opened to the public on 18 December 2013.
The Polytantric Circle was an organization that helped organize the yearly Summer solstice celebrations at Stonehenge, England.
These celebrations, called the Stonehenge Free Festival, ran from 1972 to 1984.
By the early 1980s, the festival had begun to attract a large following, and the people who helped to put the festival together year after year began to take on specific roles.
Willy X put together an annual festival list and had contact lists for bands, and the loose-knit Polytantric, an off-shoot of the White Panthers, took the lead in organising the stage and pyramid roof.
PA. Bands.
Nik Turner of Hawkwind offered valuable experience in use of setting up of the pyramid, a free alternative space, a legendary stage, which had originally made its debut with Sphinx at the Edinburgh festival Greenham, Sizewell, Stonehenge, Hyde Park.
Brixton.
From festival to campaign gigs to legalise it to peace protest to benefit, the pyramid epitomised the ambitions of a radical and vibrant alternative popular youth counter culture.
In the winter huge blocks of quartz crystals were hung inside the pyramid to purify the energies.
Stonehenge begun to grow rapidly: in 1980, 12,000 people had attended, but by '82 there were 35,000.
However, coordination between English Heritage, the National Trust, and the Polytantric Circle seemed to be breaking down.
In 1983 it was decided to move the stage to the field closer to the woods and further away from the Stones.
Sid Rawle and Big Steve the polytantric stage manager wandered across the fields past the mounds clutching a dowsing rod; it twitched downwards in a circle of daisies, the spot that was to become the site for the stage for the pyramid stage at the Stonehenge free festival.
Six days and six nights of live music followed.
In 1985 celebrations at Stonehenge were banned by English courts.
This ban was lifted in 1999, and the campaign for a new free festival summer solstice celebration continues.
The group published "The Polytantric Newsletter" and were the first to organise what became The Stonehenge Campaign. 
In 2011 English Heritage commissioned a full laser scan of the visible faces of all stones as Stonehenge in high resolution (sub-millimetre), as well as a lower resolution scan of the ground in the area known as the "Stonehenge Triangle". 
There were many problems surrounding the tour for the album, including having little room on stage due to it being decorated with Stonehenge replicas.
In a 2005 interview, Geezer Butler states that it was an error in the dimensions (feet vs. meters) that resulted in stones that were three times bigger:Ian Gillan recounted in interview that Stonehenge was indeed Geezer's idea, and that when asked for details by set buildings Light and Sound Design, Geezer simply said: "Lifesize".
Filling three containers, it was too big for any stage, so only a small part of it was used at a time, but still the band and crew had problems edging between the monoliths.
Photos of the Born Again tour show that at least some of the stones were present on stage.
Early in the tour, there was also a dwarf that was dressed to look like the demon-infant from the album cover.
The dimension problems and use of dwarfs bear strong similarities to the infamous Stonehenge scene in the movie "This Is Spinal Tap", which was released a year after Sabbath's tour.
This is undoubtedly a coincidence, however, because the "Stonehenge scene" was already in a 20-minute early demo of the film from 1982.