The terrorists planned to inflict as much carnage as possible by driving vans packed with explosives into three of the city’s busiest tourist areas, according to a report in Spanish online newspaper El Español on Saturday.
The newspaper cites police sources with information that one of the targets was Gaudi’s as yet unfinished masterpiece, the towering basilica of the Sagrada Familia.
As the most visited monument in Spain attracting more than four million visitors last year, the Catholic site is thronged with tourist crowds with queues of dozens of people snaking across the forecourt to gain entry, while thousands more linger outside to admire its spires.
Reports said that Las Ramblas was the second objective and that the busy port area, which each day welcomes hundreds of visitors disembarking from cruise ships, may have been the third target.
On Friday police said that the cell had been planning for an even bigger assault than the deadly car rampages they carried out, but had been prevented from doing so thanks to an event which was originally dismissed as nothing more sinister than a household gas leak.
An explosion in a house in Alcanar, 200km south of Barcelona, on Wednesday evening in which two people died and several were injured -- including one man who was later arrested in the wake of the terrorist attacks -- is now thought to be due to the handling of explosives being prepared for the attack.
“They were preparing one or several attacks in Barcelona, and an explosion in Alcanar stopped this as they no longer had the material they needed to commit attacks of an even bigger scope," said Josep Lluis Trapero of Catalonia's police, at a press conference on Friday evening.
It has since emerged that the group may have intended to hire a large truck, or several smaller vans, to pack full of butane gas cyclinders in order to create the maximum carnage.
But police believe that after the unexpected blast at the property on Wednesday the plotters moved to a plan B to commit "more rudimentary" attacks, which involved the vehicles ploughing into pedestrians in Barcelona and Cambrils.
Those attacks still killed 14 people and injured more than 100, of which 12 remain in a critical condition.
Interior Minister Juan Ignacio Zoido said on Saturday, that the terror cell behind Spain's deadly twin attacks has been "dismantled", although local authorities took a more cautious tone.
"The cell has been completely dismantled," he told reporters, speaking of the group that is believed to have consisted of at least 12 young men, many of them Moroccan, some teenagers.
But Joaquim Forn, in charge of interior matters in the northeastern region of Catalonia where the attacks took place, downplayed Zoido's comments.
"We can't say the investigation is finished until we locate or detain all those who we think form part of this terror cell," he told reporters.
Police are still hunting for 22-year-old Younes Abouyaaqoub without confirming reports he was the driver who smashed a van into people on Barcelona's busy Las Ramblas boulevard on Thursday.