Task: Question Answering
Input (English): Passage: There are two Campfire Circles which are used extensively during the peak camping season. The Large Campfire Circle has a Maori Gatewat which was presented by the Scouts New Zealand in 1951.
The Lime Walk, constructed by previous estate owner Margaret Chinnery, surrounds the Training Ground which was the original main lawn area of the White House. Few of the Lime trees survive to this day. On this path sits the Jim Green Gate, a 1930 tribute to Jim Green, an editor of The Scouter magazine.
The Buffalo Lawn is so called because of the replica of the Boy Scouts of America (BSA) Silver Buffalo Award that was presented by the Boy Scouts of America in 1926. This was to honour the Unknown Scout that helped William D. Boyce bring Scouting to the United States. Located there is a signpost with the directions and distances to all the World Scout Jamborees from Gilwell Park. Surrounding the Buffalo Lawn is part of the original balustrade of London Bridge which was re-built in 1820. The sections were moved to Gilwell Park after being purchased at auction in 1826.
Considered by many to be the most important Scouting site, The Training Ground is where Wood Badge training was historically held and where the Gilwell oak tree is located. Contrary to popular belief, the Wood Badge beads have never been made of Gilwell Oak. On the Training Ground sits the Gidney Cabin, a memorial to the first Camp Chief, Francis Gidney, in 1929. Across from the Gidney Cabin is the Thurman Memorial, in memory of Camp Chief John Thurman.
The caravan trailer, presented to Chief Scout Sir Robert Baden-Powell, along with a new Rolls-Royce car, during the 3rd World Scout Jamboree in 1929 is on display during the summer months. The caravan was nicknamed Eccles. The car, nicknamed Jam Roll, was sold after his death by Olave Baden-Powell in 1945.
Gilwell Park also has a number of other smaller memorials, statues, and places and objects of historical or Scouting importance. 
Question: Sections of what landmark were moved to Gilwell Park after being purchased at auction in 1826?
Output (English): part of the original balustrade of London Bridge.