Trentham Gardens, in Staffordshire, welcomed the native British species to its mile-long serpentine lake to join other wildlife such as kingfishers and water voles.
The beavers will largely be left alone to engineer their habitat, although certain trees, such as those recently planted, ornamentally valuable or used by birds for nesting and perching, will be protected with wire wrapping.
Visitors to the gardens, designed in 1759 by Capability Brown, will be able to see the beavers at work from footpaths that run through the enclosure.
Carol Adams, Trentham's head of horticulture and biodiversity, said: "This is such an amazing opportunity to establish a keystone species back into a historic landscape. It will be fascinating to see how the beavers respond to their ready-made 69-acre beaver pond.
"Our team have been preparing for this new collaborative approach to estate management, from carrying out natural coppicing of lakeside trees and shrubs to cultivating and grazing of the lake plantings and adjacent meadows. We can't wait to start seeing a unique range of habitat features, such as dams, lodges, channels and beaver pools."
Eurasian beavers fell and coppice trees, channel, burrow and build dams to create areas of greater water depth and are known as a keystone species because their work allows other wetland species to thrive, while their dams help to reduce flooding and keep more water present in times of drought.
They were hunted to extinction around 400 years ago for their fur, meat and a secretion used in perfumes but are now classed as a European protected species and recognised as native.
There are around 30 beaver enclosures in the UK, according to the Beaver Trust, which is collaborating with Trentham on the project.
Scientists see healthy wetlands as being crucial to both the climate and biodiversity crises because of their ability to store carbon through plant growth while, as an ecosystem, they contain 40% of the world's biodiversity, the UN has said.
Dr Roisin Campbell-Palmer, head of restoration at the Beaver Trust, said: "There is no doubt historically beavers existed throughout British freshwater landscapes until their extinction by humans.
"Beavers may not have known Capability Brown but will certainly benefit from his efforts. Humans have undoubtedly drastically modified these landscapes since the beavers' last presence but what we see time and time again is the remarkable ability of this animal to return and fit back in."
Alastair Budd, senior director of the Trentham Estate, said: "Our work at Trentham will establish a unique and special place for the public to engage and learn more about the species and their vital role.
"Beavers are one of the most important species in our habitats and we want to help visitors to understand why this once-extinct UK native should be back in the English countryside, helping to restore our ecosystems and mitigate the impact of climate change."