Project Horizon is the mysterious codename for Alton Towers’ forthcoming indoor rollercoaster.
Expected to open with the rest of the Staffordshire theme park in mid-March 2025, planning permission has already been agreed.
Construction is still to begin on what is a highly secretive project, which first emerged in November 2022.
The ride – confirmed to be a rollercoaster in planning documents – will be housed within a large 19-metre (64-foot) tall building.
Significant excavation below ground level has been ruled out, meaning the maximum feasible height of any track drop would be little more than 50 feet.
‘Coaster Corner’
The main building will also be 71 metres (233 feet) long by 46 metres (151 feet) wide, with a smaller entrance room attached to the front.
That floorspace is similar to the main façade-fronted section of Blackpool Pleasure Beach’s Valhalla dark ride.
Project Horizon’s location is the site of the former Alton Mouse rollercoaster, which closed in 1991.

It would lie to the west of the Alton Towers Dungeon, in an area colloquially referred to as ‘Coaster Corner’.
A new plaza is also going to be built in front of the ride’s building, as well a large themed ‘entrance portal’, five metres in height.
Construction on the £12.5 million project will begin later this year, and is expected to take 12 to 14 months.
Project Horizon may become dubbed as ‘Secret Weapon 9’ if Alton Towers continues the tradition of naming major new rollercoaster projects in this way.
Manufacturer speculation
While the rollercoaster’s manufacturer has not been confirmed, Intimin has been tipped on the rumour mill.
And Intamin might fit the brief: a relatively compact ride undoubtedly requiring innovative – if not pioneering – technology.
But if the £12.5 million “approximate” budget is accurate, that may mean another manufacturer has been selected.
Creative lead designer John Burton has himself hinted at Rocky Mountain Construction (RMC) being involved with Merlin Entertainments at some point in the future.

But the floorspace might make RMC’s traditional designs a struggle, and the playful nature of the hint means it cannot be taken seriously, at least not yet.
Some people have pointed to RMC’s new ‘Wild Moose’ family coaster concept, which might just about fit inside the building.
But it would need to have some truly exceptional theatre to make it marketable as Alton Towers’ next big thing.
Extra visitors
Whatever Project Horizon turns out to be, it will certainly be marketed as a unique, thrilling, and exciting experience.
The planning application claimed the ride’s introduction would add about 150,000 visitors to Alton Towers each year.
“It is expected that the construction of the new coaster and ancillary facilities will increase visitor numbers by approximately 150,000 annually,” consultants Lichfields said.
However, overall visitors to Alton Towers are not expected to exceed the 3 million admissions seen in 2010 following the highly successful marketing of the Thirteen rollercoaster.

One specific detail revealed by the plans was that the building would not have a water supply, seemingly ruling out any type of water ride or effects.
Room 1 will be the pre-show and batching area, with the larger Room 2 hosting the main ride.
A large, ring-shape, and cantilevered object will tower above the roof and entrance to Room 1, in another apparent themed item.
The ring will be angled at 14 degrees upwards as it projects out from the main building.
Due to the enclosed nature of the ride, virtually every other detail about Project Horizon is guesswork, and will remain so right up until March 2025.