Pictures have emerged of the building in the Mabera area of Sokoto, scene of the botched rescue attempt by British and Nigerian special forces, which resulted in the deaths of Chris McManus and Franco Lamolinara.
The British and Italian construction workers were taken captive by terrorists in May last year.
The men died on Thursday as Nigerian troops and UK Special Boat Service (SBS) commandos launched a rescue mission to end their nine months in captivity in the West African country. During the fire fight, the terrorists burnt tyres before trying to escape.
The building where tyres were burnt while kidnappers attempted to escape during the failed rescue operation.
The killing of the hostages has ignited a diplomatic row between London and Rome, with Downing Street defending its failure to inform Italy ahead of a hostage rescue operation.
Italian President Giorgio Napolitano said that the UK's failure to tell Rome was "inexplicable" and demanded a political and diplomatic explanation.
The UK's ambassador in Rome is understood to be in contact with Italian authorities, but Downing Street said it had so far received no official complaint from the government of Prime Minister Mario Monti.
A soakaway pit in the building.
Prime Minister David Cameron's official spokesman told reporters that Britain and Italy had been in contact ever since the men were first kidnapped last May, and that the Government's Cobra emergency committee had met around 20 times to discuss the case.
"We contacted the Italians yesterday as the operation was getting under way, but this was a very fast-moving situation," said the spokesman. "Our priority was to respond to the situation on the ground and to do everything we could to try and secure the safe release of the hostages."
Mr Cameron said on Thursday night that Mr McManus and Mr Lamolinara had been in "imminent and growing danger" and an opportunity had arisen to attempt to rescue them.
"The terrorists holding the two hostages made very clear threats to take their lives, including in a video that was posted on the internet. Preparations were made to mount an operation to attempt to rescue Chris and Franco. Together with the Nigerian government, I authorised it to go ahead, with UK support."
More scars from the tyre burning by the terrorists.
Exact details of how Mr McManus died remain unclear, but Mr Cameron said initial indications were that the contractor and Mr Lamolinara were "murdered by their captors, before they could be rescued".
In December last year, a Nigerian group calling itself "Al Qaida in the land beyond the Sahil" announced it had captured McManus.
It released a hostage video to Nouakchott News Agency claiming it had kidnapped the Briton and showed a blindfolded and bearded man in an orange vest.
Three men in dark clothing stood behind him armed with rifles and a machete.