Average house prices in 90% of council wards in Wales are lower than 10 years ago, BBC research has shown.
Aberdulais in Neath Port Talbot saw the biggest fall but the findings only looked at sales, with one agent saying it did not give a fair representation of prices.
The study analysed more than eight million residential property transactions using Land Registry data.
Adjusted for inflation, prices in 90.5% of wards were lower in 2017 than 2007.
At the other end of the scale, some parts of London have seen massive increases in house prices compared to a decade ago.
How have house prices changed since the recession?
Average house prices from 2007 to 2017, not adjusted for inflation
The findings do not compare the value of people's homes and how that has changed over the 10 year period but the average price for all homes sold in that ward.
But in April, a new index by the Principality found the average price in Wales was now at £174,319 compared with a peak of £170,142 in October of 2007.
According to the BBC data, the average house price in St Arvans in Monmouthshire is up by 23%, the rise driven in part by the Severn bridge tolls being scrapped next year, according to local property experts.
Chepstow-based estate agent Peter Moon said the county as a whole was desirable but "interest really jumped" from Bristol and the south east when it was confirmed tolls would be axed.
"The important driving factor here is housing and jobs," he said.
"Other parts of Wales, possible employment is more of an issue and that's where there has been a drag in house prices."
In Aberdulais in 2007, the average house price was £143,000 but in 2017 the figure was £65,000 - a drop of 64%.
Leighton Williams, from Alison George Estate Agents in Neath, said: "Aberdulais is an interesting area where perhaps 50% of the housing is social housing, therefore can't be sold.
"In the last 12 months, there have only been 14 sales in Aberdulais - four of which were sold at a price lower than the previous sale price.
"One of those was considerably less, 28% less than the previous sale price.
"When you've got such a small amount of transactions, one large drop can skew the figures quite considerably," he said.
"The average house price for that area is about £120,000 which is pretty standard for Neath as a whole.
"There are a lot of flats which will sell in the sort of £60,000 price point, but there are also some very nice individual detached properties in Aberdulais which will sell in the £300,000-plus price point."