We often use 'been' for completed visits to a place. So you would say : Andrea has never been to Seville before, because that sentence would imply that she has gone and come back. If, however, you use 'gone', as in : 'Has Andrea gone to Seville?', then you would understand the meaning to be that Andrea is currently in Seville or travelling to it. She has not come back.

Both sentences are correct in terms of grammar, but we'd normally say "Andrea has never been to Seville before" to express the idea that it is her first visit to the city. It would mean that she is in Seville for the first time. 'Been' emphasises the person's presence in a particular place. 'Gone' emphasises the movement: idea that someone is not here because they have left to go to another place. Take a look at these two examples. Let's imagine that Andrea is away from work because she is attending a conference in Seville at the moment. Her colleagues are talking about her: Andrea's not at work today. Where is she? She's gone to Seville. (She's in Seville now) Now imagine that she has come back from the conference. Two different colleagues might have this conversation: I see that Andrea's back at work. Has she been ill? No. She's been to Seville. (This means that she was there and now she has returned) I hope that makes sense.

The first one is correct