"I went to the cinema last week", or "I was at the cinema last week"?

Both, depending on meaning.

"I went to the cinema last week, but I did not care for the movie they were showing so I never went in."

"I was at the cinema last week when it collapsed because of the earthquake."

"I went to the hospital to take my sick grandmother some flowers."

"I was in the hospital all last week, but only for observation; they decided in the end not to operate."

"I go to confession at my local church every Sunday."

"I was in Church when you tried to telephone me."

"He gets caught every time and goes to jail."

"He has been in and out of jail his whole lifetime."

"To go" indicates motion, "to be" indicates physical location. Obviously the two ideas may overlap and if you go somewhere you usually do something (such as watch a movie) on your arrival, and if you are some place, you must have already traveled to get there!

Which construction is prefered by English speakers when the meanings do overlap, I have no idea. Perhaps someone with nothing better to do could start counting!

I can only give"English"English usage,but I don't think there's any difference in this case-

1) the 1st. version can be said alone=it doesn't need anything else to be a sentence.

2) the 2nd. version needs more to be complete; for example -"I was at the cinema last week,and there was a special offer on pop-corn"

Hope thats what you wanted!

Both are correct.

However, 'I was at the cinema last week' is probably used more commonly when someone is talking about an event that occured at the cinema, such as 'I was at the cinema last week, when this middle aged man kept chewing really loudly!' This is not mandatory though.

Overall both examples are correct.

Both are correct but use in different conversation.

You was at the cinema.

You went to the cinema.