A group with al-Qaeda links discussed bombing nightclubs and attacking gas supply networks, a court has heard.
The men, one of whom cannot be pictured, deny all the charges
The group of seven men considered an attack on Kent's Bluewater shopping centre, and had a list of synagogues, the Old Bailey was told.
One suspect was allegedly involved in a plot to buy a "radio-isotope bomb".
Four men, of Crawley, West Sussex, one of Horley, Surrey, one of Ilford, east London, and one of Luton, Bedfordshire, deny conspiring to cause explosions.
Four of the men also deny having chemicals suitable for bomb-making. The trial is expected to last five months.
Suspects Salahuddin Amin, 31, from Luton, and Omar Khyam, from Crawley, were alleged by the prosecution to have received training in explosives and use of the poison ricin in Pakistan.
The group's plan to make bombs in the UK involved 600kg (1,300lb) of ammonium nitrate fertiliser stored at an Access Self Storage depot in Hanwell, west London, as well as a smaller amount of aluminium powder, the prosecution said.
But staff at the depot became suspicious and notified police, who replaced the fertiliser with a similar-looking inert material and started a surveillance and bugging operation of the suspects.
The prosecution suggested plans for attacks were in the final phase when Special Branch and anti-terror police intervened.
On 22 February 2004, a listening device at the Uxbridge home of defendant Jawad Akbar, picked up members of the group talking about possible targets.
David Waters QC, for the prosecution, said: "Jawad Akbar referred to attacks upon the utilities, gas, water or electrical supplies.
"Alternatively, a big nightclub in central London might be a target."
Mr Akbar allegedly said: "The biggest nightclub in central London, no one can put their hands up and say they are innocent - those slags dancing around."
Later, he was recorded saying: "I think the club thing you could do but the gas would be much harder."
The same suspect was allegedly heard informing his wife that he might be trained up for a "big mission".
Another suspect Waheed Mahmood worked for Morrisons Utility Services, a Transco contractor.
National Grid Transco runs the high voltage electricity network in England and Wales and Britain's high-pressure gas infrastructure.
Omar Khyam allegedly proposed pubs and nightclubs as targets
Mr Mahmood was allegedly recorded saying the Madrid bombings were "absolutely beautiful", while Shujah said it would have been "fantissimo" if they had been staged during the holidays to target families.
Waheed Mahmood raised on one tape the issue of bombing the Bluewater shopping centre on a Saturday.
He allegedly said: "I don't know how big it would be, we haven't tested it, but we could tomorrow - do one tomorrow."
At Shujah's home in Crawley, police found a list of synagogues including sites in London and Manchester, with the men's fingerprints on, Mr Waters said.
"The likely purpose of this information, you may think, was in relation to potential targets," said Mr Waters.
The court heard a letter was found at defendant Anthony Garcia's girlfriend's house in north London, which seemed to be Mr Garcia saying farewell to his younger brother.
It read: "Don't think this is our last time. We will meet soon, Isallah, either in this life or the other."
The court earlier heard that in 2001, when defendant Salahuddin Amin had been in Pakistan, he had been asked by Abu Munthir, a man he had met at a mosque in his hometown of Luton, to contact a man named Abu Annis about a "radio-isotope bomb".
Mr Waters told the jury: "Amin did so via the internet and Abu Annis said they had made contact with the Russian mafia in Belgium and from the mafia they were trying to buy this bomb."
Mr Amin later told police he did not believe the offer could be genuine.
"In his own words, he didn't think it was likely 'that you can go and pick an atomic bomb up and use it'," Mr Waters said.
Mr Amin, 31, Mr Akbar, 22, Mr Khyam, 24, his brother Shujah Mahmood, 19, and Waheed Mahmood, 34, all of Crawley, West Sussex, Anthony Garcia - also known as Rahman Adam - 23, of Ilford, east London, and Nabeel Hussain, 20, of Horley, Surrey, deny conspiring to cause explosions.
Mr Khyam, Mr Garcia and Mr Hussain deny possessing ammonium nitrate fertiliser.
Mr Khyam and Shujah Mahmood deny possessing aluminium powder.
The case was adjourned until Thursday.