I know nothing of clan citadels, because I am not in a clan. But I would still want to complete these tasks. Is that possible without the need of joining a clan? And how can I visit someone else clan citadel? You just click the portal and enter a clan name or something like that?

Thanks for answering :P

There is 2 tasks to do with Citadels, 1 which you have to visit anyones Citadel and the other you have to visit your Clan's citadel.

There are actually 4 tasks listed in the tip.it task guide.

 

But it looks like ya just have to be a guest of someones clan citadel and you'll complete them all