I discovered Category Theory one year and a half ago and I got addicted. I studied some of the basic concepts of this branch (limits, adjunctions etc.), including some sightseeing into abelian categories and cohomology theory and some look at sheaves on sites for my undergraduate thesis. I also plan in the immediate future to try and get confident with triangulated and derived categories, if I can bear the subject.
I'd now like to go into deeper studies in CT, so I'd appreciate to have some references (books or on-line sources) and suggestions, especially about what topics should I cover (and discover), also in view of possible research outcomes. For the moment, I'd like to stick to arguments which are as near as possible to "pure" Category Theory, without studying it through its applications in different fields of mathematics (even though this do match my interests and is somehow unavoidable, I think, for a reasonable understanding of CT itself).
For sake of concreteness, I can say I feel rather attracted from Higher Category Theory (even if I don't know much about it nor about how much background it is needed) and Categorical Algebra, but I'm open to any other (maybe more approachable or more fundamental) suggestion for further studying.
Thanks in advance.