Work to prepare the first horizontal fracking site in the UK for shale gas extraction has begun in Lancashire.
The government approved energy firm Cuadrilla's plans to frack at the Preston New Road site at Little Plumpton in October last year.
The firm said it started site construction work on Thursday after Lancashire County Council agreed planning conditions had been met.
It is "an important milestone", chief executive Francis Egan said.
Anti fracking campaigner Tina Rothery said the fight against fracking will continue "both locally and nationally... to counter this clear and present danger".
Cuadrilla said drilling will commence in approximately three months after the surface site, which it describes as "roughly the size of a rugby pitch", is prepared.
A new site entrance, access road and well pad will be constructed before a protective membrane is installed "to create an impermeable barrier underneath the site", the firm said.
Mr Egan said the work will "be undertaken to the highest safety and environmental standards" and monitored by the firm as well as by regulators and academics.
"Twelve months from now we hope this work will prove the economic viability of this indigenous shale gas resource in Lancashire which will help improve energy security for the nation," he said.
Anti-fracking activist Ms Rothery said the move "shows complete and utter disregard" for local people as "there are two outstanding legal challenges" to the decision to allow fracking at the site.
Two requests for a judicial review have been submitted by Preston New Road Action Group and an individual.
Cuadrilla said in a statement: "Whilst we are respectful of the democratic right of the two parties who have issued statutory challenges... this legal action does not prevent us from continuing with our planned operations".
Hannah Martin, campaigner at Greenpeace UK, said support for fracking is "at an all-time low" and that resistance will continue until the government "moves away from this dirty technology and backs renewable and smart technologies instead."
A second Lancashire site, Roseacre Wood, has not yet been given the green light amid concerns over the impact on the area.
The council had refused permission to extract shale gas at both sites on the grounds of noise and traffic impact but the government overruled the decision for the Preston New Road site.
Gillian Wood, from Blackpool, who was at the site, said it is "appalling that this is being forced on us, our countryside and our climate, and we won't stand for it."
"As someone who lives in the local area, I'm shocked that Cuadrilla has started moving in with their trucks and equipment, especially when two legal challenges still aren't resolved."
Police tweeted that road works have begun on the A583 with temporary traffic lights near the site.
Cuadrilla has set up a hotline for enquires about the work.
What is fracking?
Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside. Water, sand and chemicals are injected into the rock at high pressure which allows the gas to flow out to the head of the well.