The RAF's Avro Lancaster could carry 14,000 lbs of bombs. By the end of the war specially modified versions were lifting 22,000 lbs. One common load was a 4000ld HC and 20 incendiaries or20 250lb bombs. See photo on link
http://en.wikipedia.org/wiki/Blockbuster_bombThis looks like a 4000lb HC Blockbuster.
This is a link to a similar bomb being defused in 1977. According to Der Spiegel they find a bomb every week just not this big.
http://www.spiegel.de/international/germany/0,1518,584091,00.html"In the whole of Germany, more than 2,000 tons of American and British aerial bombs and all sorts of munitions ranging from German hand grenades and tank mines to Russian artillery shells are recovered each year. Barely a week goes by without a city street or motorway being cordoned off or even evacuated in Germany due to an unexploded bomb being discovered.
"Unearthed munitions that can be transported safely are taken to a detonation ground where they are exploded or have their explosives removed. But many bombs -- and all bombs with delay-action detonators -- are too dangerous to be moved and must be either defused or detonated where they are found.
Weise said it will take at least another 20 years before Brandenburg's bombs are cleared, and that the state is particularly contaminated with American delay-action bombs which have become so unstable that it will soon be impossible to defuse them safely. The bombs are on a hair trigger because their chemical detonators have been worn down by acetone vapors as they have lain lurking in the ground for over 60 years."
According to Wikipedia; "The bombs then called Blockbusters were the RAF's 4,000 lb — also known as a cookie — 8,000 and 12,000 lb (1,800, 3,600 and 5,400 kg) HC (High Capacity) bombs. These bombs had especially thin casings that allowed them to contain approximately three-quarters of their weight in explosive, with the 4,000 pounder containing over 3,000 lb (1,360 kg) of Amatol. " 1.8 tonnes (metric tons) would be the equivalent of 4000lb (Imperial pounds)
Tallboys and Grand Slams (earthquake bombs) were even bigger.