People are being warned to stay away from the derelict Hornsey Rise care home in Wellsborough.
Police in Market Bosworth said people have been travelling from outside the county to visit the site which has been repeatedly targeted by vandals and arsonists since it closed in 2013.
In a Facebook post, officers said: "This site is extremely dangerous with concealed underground drainage, unstable floors in the buildings and an endless list of trip & fall hazards.
"As exciting as some people may think this place is- is it really worth potentially seriously harming yourself- or worse!"
The force said it was aware of some websites claiming the site was safe, but warned that is not the case, and as it's private property, anybody on the premises is trespassing.