This was the theory behind Canadian artist Peter von Tiesenhausen's decision to bury a sculpture almost four metres underground, beneath a sewer at the main crossroads in the city of Sarnia, Ontario.

BBC: Why make art no-one can see?

Mike Chinoy, a former CNN correspondent who has visited North Korea 15 times, said the current confusion about Pyongyang's capabilities recall a similar episode in 1998, when U.S. spy satellites discovered an underground complex at Kumchangri, not far from North Korea's main nuclear facility at Yongbyon.

CNN: 5 things we still don't know about North Korea's nukes

The compound is on three lots and would include a main home of 42, 000 square feet part of it underground a guest house, pool cabana, gate house and another residence of up to 20, 000 square feet.

WSJ: Living

They chalked up their problems in the New York area to devastating flooding that, in addition to knocking out power, disabled backup generators and disrupted the underground cables that carry calls, texts and Web searches from cell towers back to the main networks.

WSJ: Outages Expose Wireless Carriers' Backup Plans

Whatever the Swedish government claims, social workers who deal with prostitutes say the law has simply driven the sex trade underground, thereby making it harder to clamp down on trafficking in foreign women, one of the law's main aims.

ECONOMIST: Sex for sale, legally | The