Caravans were set alight on consecutive days at the notorious fly-tipping hotspot of Norwood Lane in Paston Ridings.
Fire crews were called out at 6.12pm on Saturday and 7.43pm on Sunday to the site.
Both fires were believed to have been started deliberately.
Anyone with information on the fires is asked to call police on 101 or submit an online report at www.cambs.police.uk.
Norwood Lane is well known as a city grot spot, despite security guards and cameras being installed there to trying and tackle the problem.