CCTV cameras are set to be switched on in the Dyfed-Powys Police area, three years after they were turned off.
The first cameras have been set up in Builth Wells, Powys, ahead of next week's Royal Welsh Show.
The police and crime commissioner had pledged to reintroduce CCTV as part of a £1.5m project.
It will take 18 months to complete, with 116 cameras in 17 towns monitored around the clock in Powys, Ceredigion, Carmarthenshire and Pembrokeshire.
Commissioner Dafydd Llywelyn announced an intention to reintroduce the cameras last year.
His predecessor Christopher Salmon stopped CCTV monitoring after a report in 2014 concluded removing cameras did not result in significant rises in crime.
However, Mr Llywelyn said he believed the cameras had a role to play in the fight against crime.
He said: "Sadly, violent crime is on the increase. It's not a phenomena unique to Dyfed-Powys, it is something happening across the whole of England and Wales.
"But this will be an opportunity for us now to have the CCTV system in place to support us in, ultimately, the fight across violent crime in our towns."
A monitoring room is due to be be fully operational by mid-August, coinciding with the installation of cameras in Carmarthen town centre.
Camera locations have been selected by mapping hotspots for crime and anti-social behaviour with the public involved "to ensure it is something that they want to see as well", according to Assistant Chief Constable Richard Lewis.
They will be used at Aberystwyth, Ammanford, Brecon, Cardigan, Fishguard, Haverfordwest, Llandrindod Wells, Llanelli, Milford Haven, Newtown, Pembroke, Pembroke Dock, Saundersfoot, Tenby and Welshpool.
Mr Lewis said: "The new system is far more developed than we would have had years ago.
"We're excited to see how it develops, whether it is intelligence gathering, prevention or detection of crime."