A new visitor centre was unveiled on Monday at the oldest recognisable human dwelling in Britain.
Kents Cavern in Torquay is Britain's oldest scheduled Ancient Monument, with artefacts showing continuous occupation from every period in history.
The tourist attraction is one of the most important Palaeolithic caves in Northern Europe.
It holds spectacular geological formations and significant prehistoric finds, some over 700,000 years old.
Famous visitors to the Torquay attraction include Beatrix Potter in 1893 and Agatha Christie in 1923.
The cavern has been privately owned by the Powe family since the early 20th Century.
The land, which was part of Lord Haldon's estate, was sold to Francis Powe in 1903.
A carpenter by trade, Mr Francis Powe used the cavern as a workshop to make bathing huts and beach huts for Torquay sea front.
The current owner and managing director, Nick Powe, says Kents Cavern is an important centre.
Finds include hand axes, which have been dated as 450,000 years old, and a human jaw bone dating back 31,000 years.
Mr Powe said: "It's a remarkable place which unfortunately has never had the support of the academic world in terms of funding.
"We've had to raise the £500,000 to build the visitor centre privately, as we don't qualify as a charity.
"The new centre has modern facilities, exhibition areas, a restaurant and shop."
The visitor centre has been built on a spoil heap from excavations in 1860.
Before work began, archaeologists examined the spoil heap and found artefacts showing continuous occupation from every period in history.
Kents Cavern became a Scheduled Ancient Monument giving the site a statutory scheduling by English Heritage in 1957.
The hillside, woodlands and the internal landscape of the caves are designated a Site of Special Scientific Interest under the statutory regulations of English Nature.