The 15-ton bell was cast on April 10, 1858, at the Whitechapel Bell Foundry in east London, although it was another year before it first rang out from Parliament's clock tower.
"We are going to toast Big Ben's health at the end of the working day," said Mike Backhouse, the foundry's works manager. "Whether we'll sing 'Happy Birthday,' I don't know."
Big Ben has given its name to one of London's most famous landmarks Parliament's 19th-century neo-Gothic clock tower, designed by Charles Barry. The tower is popularly known as Big Ben, although the name actually refers only to the Great Bell inside.
The Whitechapel foundry was marking the anniversary by casting 3 1/2-inch (9-centimeter) replicas of the bell one for every two years of its life. They will be sold for about $200 apiece.
Founded in 1570 and officially Britain's oldest manufacturing company, Whitechapel is one of only two remaining bell foundries in the country. Its other creations include Philadelphia's Liberty Bell and the Bell of Hope, given to New York by Londoners on the first anniversary of the Sept. 11, 2001, attacks.
Backhouse said Big Ben remains the largest bell every made at the foundry, and would have presented a "massive challenge" to 19th-century bell-makers.
"The technical challenge would have been making the mold for the bell strong enough that it wouldn't have been broken or distorted by 13 1/2 tons of molten bell metal," Backhouse said.
The bell cracked soon after it was installed as an earlier version had during testing. Officials simply fitted a smaller hammer and turned the bell so the hammer wouldn't strike the crack.
The bell, crack and all, remains in use, and has become a symbol of reassuring reliability. During World War II, Big Ben's resonant bongs became a sign of resistance to Nazi bombs.
Parliamentary officials plan to mark the 150th anniversary of Big Ben's first bong with a ceremony next year.
The bell has been silenced briefly by weather, mechanical failure and accident, and for four periods of maintenance in 1934, 1956, 1990 and for six weeks last year.
Bookmaker William Hill is offering odds on the bell failing to chime in its anniversary year. The odds are 100/1 of Big Ben being silenced by bird interference, 150/1 on it being stopped by ice or snow, and 1000/1 on one of the clock's hands falling off.
By JILL LAWLESS