hay castle is putting the imposing castle , which towers above the town of hay-on-wye on the welsh border , at peril .
but now the medieval stronghold that has already endured so much is at risk of falling to a new army that infestation of deathwatch beetles is caused by their larvae , which burrow inside the wood , weakening them as they go .
it was damaged by fire during the rebellion of welsh chieftain owain glyndwr in 1401 , and victorian terraced gardens .