Does anyone know what the longest pro game of go ever played is, and know some details about it?

I tried to search this forum, but was not able to find more about this. I mean not to ask for longest time settings or number of moves, but total time of duration of a game. I was also not able to find the answer on Sensei. Sensei only mentions it took more than 8 hours (!) for a specific move.

I am interested to know who the players were, when and where the game was played, how long the game took, etc. If you have information about the longest match (multiple games; total time span) and/or longest championship, I am also interested in learning more about that as well.

Here's cut & paste from the (copyrighted) GoGoD Encyclopaedia. I'm not prepared to do more than this without knowing why the request was made - had too many cases of "Oh I was just curious."

Kindly thank you for your reply.

A youth member (10 years) came up with this question during a club evening the other day. Noone knew the answer. I think he was just spontaneously curious.

Do you mean the longest time actually spent at the board 'on the clock' for the game as John answered, or longest time between the game starting and finishing? For the latter correspondence games easily get big times: I think my longest was 11 months and I'm sure in the play by mail days several years were not uncommon. And those long pro games of old were split into many sitings but I'm guessing months rather than years. Maybe I should finish my Malkovich game with Magicwand...

I think this young club member is not familiar with correspondence games. I think he meant 'regular' games.
That's why I inquired about pro games. Those are not correspondence, as far as I know.

Indeed not in the typical sense, but some had breaks (e.g. moves 1-60 one day, 61-84 a few days later etc) and the players studied the game during the breaks: a famous example being Shusai vs Go Seigen where the all-but-confirmed rumours of one of Shusai's pupils being the one who found the brilliant myoshu that made Shusai win the game. IIRC in that game Shusai had the right to choose when to adjourn and used it to his advantage, which was behind Kitani's insistence in a fairer setup for their later game.

I played a correspondence game of go covering the first two years of my play (and improvement) - my opponent was dreadfully slow (he had almost 1,000 games running at one point, ridiculous) and only resigned when finally everything on the board was dead.

Stu Horowitz and I once has a set of 5 correspondences games going, back in the early 90s, which went on for around 5 years and we never did finish them. I still have them somewhere

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).