Germany's narcotics investigators are increasingly being called out to inoffensive looking old factories or unused school buildings. The reason is that they are being used as places to grown cannabis. The recreational drug is as popular as ever but less quantities are being imported than ever before. There's no need to as, according to experts, several hundred tons of the drug are produced in Germany illegally every year. The government in Berlin now recognises that it has spent years underestimating the drug's dangers.