Nagano City, the capital of Nagano Prefecture in the Chubu region, is most famous for Zenkoji, one of the more visually impressive temples in Japan. In terms of size and grandeur, as well as historical and cultural background, Zenkoji does not lose out to Sensoji in Asakusa, Tokyo. The temple is well-known for housing the Hibutstu, or �Hidden Buddha�, which is displayed to the public every six years.

But the unique attraction of Zenkoji is the underground passage that exists within the main temple building. Somewhere in the passage lies a key that is said to grant enlightenment and salvation to anyone who can find and touch it. The key represents the Western Paradise of the Amida Buddha. Unsurprisingly, you need to pay an extra couple of hundred yen to enter the passage�

The underground passage is big enough for two reasonably-sized people to walk side-by-side, though those who are very tall will find this little journey a tad uncomfortable. Furthermore, the course of true enlightenment never did run smooth (Don�t get mad now, William) - the path does not go in a straight line; it winds and turns from time to time, so don�t expect a too easy time in there. At least there are no branching paths�

But the worst (or best, depending on how you look at it) thing about this passage is that it�s completely pitch-dark � You can see absolutely nothing in here, so it can get pretty scary (or exciting). Light of any sort is strictly prohibited in the passage � not even light from cell phones or watches is allowed. Be prepared to face the gods� wrath (or the temple monks�, at least) if you disobey this rule.

What�s more, the passage goes on for several minutes at a slightly-below-average pace (you wouldn�t want to walk at a normal pace or faster unless you�re nocturnal. No, seriously.), so your time spent there can feel like an eternity. This is definitely not a place for the claustrophobic. The good news is, because the passage is so popular, you can rest assured that you will never be alone in there � there�re always people walking in front of and behind you, barring extremely off-peak periods. And thankfully, a sign just outside the entrance points out helpfully that the key is located on the right wall, so just keep feeling the right wall as you walk along, and you won�t miss it.

As for the key itself, this baby feels pretty large � about the size of a large child, and you�ll know you�ve found it when you can feel a long and metallic cylindrical object. It�s attached to the wall though, so don�t even think about taking it away with you. The key is located quite near the exit.

Zenkoji is conveniently located in the city centre, and is served by several frequently departing buses from JR Nagano Station. However, it is possible to go there on foot from the station, and the journey takes about 15 minutes, if you walk briskly. JR Nagano Station itself is 90 minutes from Tokyo by Shinkansen. Zenkoji definitely appeals to a wide range of visitors � from history/culture buffs (because the temple is rich in history and culture) to Buddhists (for the opportunity to literally find the key to Buddhist paradise) to casual tourists (for the sheer cool factor of navigating the dark underground passage and finding the key).