What did I do wrong?

[Lion-O, Lord of the Thundercats]

I got to Gorn Saren with the hydra head on the cart. Once I got through the cutscene and spoke to the Mason guy I went up the road, climbed a staircase and got arrested.

I had to pay 5000g to get out of prison.

I am unaware climbing staircases is a criminal offence?

[Old Goat]

Climbing a staircase is not illegal. I've climbed every staircase in GS and Cassardis with no problem. Perhaps you stole something earlier in the game and thought you'd gotten away with it or inadvertently assaulted an NPC somewhere along the way (maybe those two guys in the little shack on the way to GS from Cassardis). U might want to bone up on what the Wiki has to say about "crimes ddda" just to be sure you don't wind up in Jail in the future.

[MP]

Originally posted by Old Goat:

Climbing a staircase is not illegal. I've climbed every staircase in GS and Cassardis with no problem. Perhaps you stole something earlier in the game and thought you'd gotten away with it or inadvertently assaulted an NPC somewhere along the way (maybe those two guys in the little shack on the way to GS from Cassardis). U might want to bone up on what the Wiki has to say about "crimes ddda" just to be sure you don't wind up in Jail in the future.

this 100%

[Grr. [SG CMD] Majah Lazah]

don't run while in town unless something is on fire or being attacked

[Cyanmurder]

Crime doesnt pay, what you gonna do when they come for you.

[Brighteluden]

If you do the crime you gotta do the time bucko

[AvG]

The most common crime is accidentally swinging a weapon attack at a person in town, its pretty easy to have that happen early game when learning or talking to people.
the second one is lifting someone up in town, even if you carefully set them down a guard may decide you are a criminal.

[Lion-O, Lord of the Thundercats]

Originally posted by Old Goat:

Climbing a staircase is not illegal. I've climbed every staircase in GS and Cassardis with no problem. Perhaps you stole something earlier in the game and thought you'd gotten away with it or inadvertently assaulted an NPC somewhere along the way (maybe those two guys in the little shack on the way to GS from Cassardis). U might want to bone up on what the Wiki has to say about "crimes ddda" just to be sure you don't wind up in Jail in the future.

I never picked anything up, nor hit a NPC. Like I stated, I entered the city with the Hydra head, cut scene, spoke to mason, then went about 20 ft away, went up a staircase, guard at the top stopped me and said 'dont make any trouble...."

and was then in the jail......

[Velber]

Originally posted by Lion-O, Lord of the Thundercats:

Originally posted by Old Goat:

Climbing a staircase is not illegal. I've climbed every staircase in GS and Cassardis with no problem. Perhaps you stole something earlier in the game and thought you'd gotten away with it or inadvertently assaulted an NPC somewhere along the way (maybe those two guys in the little shack on the way to GS from Cassardis). U might want to bone up on what the Wiki has to say about "crimes ddda" just to be sure you don't wind up in Jail in the future.

I never picked anything up, nor hit a NPC. Like I stated, I entered the city with the Hydra head, cut scene, spoke to mason, then went about 20 ft away, went up a staircase, guard at the top stopped me and said 'dont make any trouble...."

and was then in the jail......

you prob went to an area you werent allowed in yet, if i remember some areas are blocked off until you progress further through the main story

[alienstookmybeer]

What color did you make your character?

[Something completely different]

Sounds like you went to the Duke's quarters at night to me.

[Velorien]

Originally posted by Something completely different:

Sounds like you went to the Duke's quarters at night to me.

That shouldn't be possible until you've completed the Wyrm Hunt quests. The guards turn you away at the gate.

Originally posted by Old Goat:

Climbing a staircase is not illegal. I've climbed every staircase in GS and Cassardis with no problem. Perhaps you stole something earlier in the game and thought you'd gotten away with it or inadvertently assaulted an NPC somewhere along the way (maybe those two guys in the little shack on the way to GS from Cassardis). U might want to bone up on what the Wiki has to say about "crimes ddda" just to be sure you don't wind up in Jail in the future.

The game doesn't have a "stealing" mechanic (with the exception of the duke's treasury, which you won't be getting into by accident), and Gran Soren guards don't care about anything you do outside the city.

Honestly, if OP really didn't threaten/assault any NPCs, this sounds like a bug.

Also, for future reference, there are two other ways to get out of jail.

1) Wait a full in-game day
2) Use skeleton keys (combine iron with shackles, which are dropped by bandits) to get to the secret passage in one of the cells.