A £12m scheme to boost tourism and create up to 300 jobs in the Heads of the Valleys has been announced.
More than £5m will be spent on improvements at Bedwellty House
The investment, by the assembly government, local councils and private sector, aims to attract nearly a quarter of a million visitors a year.
Projects include extending Pontypool and Blaenavon railway near Big Pit and restoring historic buildings.
But a business expert warned there might not be enough places for visitors to stay in the region overnight.
The strategy is designed to develop the tourist attractions that will attract not just day trips but also short breaks and activity holidays.
The Welsh Assembly Government said this could unlock the tourism potential of the region.
Under the plans, Bedwellty House and Park in Tredegar, a former ironmaster's residence, will be restored and upgraded, subject to public consultation.
A "contemporary garden" on the theme of "the environment and climate change" will be built on the former Markham Colliery site near Blackwood.
Cyfarthfa Park in Merthyr Tydfil is to be established as an "activities and events venue" and the visitor centre at the Dare Valley Country Park, to the south of Brecon Beacons, will be upgraded.
Deputy regeneration minister Leighton Andrews said he believed the tourism industry in the area was already worth more than £100m.
"We think this package overall, when we've leveraged in the additional private investment, will contribute to probably about another 250 or 300 jobs in the area, specifically in tourism," he said.
"What we think is that people need to understand that the valleys have changed radically, that they are green, that they offer wonderful outdoor activities but they also offer fantastic industrial heritage as well."
But Dr Calvin Jones from the Cardiff Business School was worried the region might not be in a position to take full advantage of the new investment.
"If you can imagine a quarter of a million people staying in the valleys overnight - that's where the really big hits come in terms of economic impact," he said.
"And that's the difficulty - finding the capacity to host all those visitors from the beginning to the end of their trip, rather than just making it an hour or two out of a longer trip elsewhere, where the big money is spent."