Hilbert's 1900 lecture, Gödel, Turing, and Church, etc.
Turing machines, Church-Turing thesis, decidability, halting problem, Reductions between problems, Rice's Theorem. (Sipser text, Chapters 3, 4, and parts of 5 and 6).
Sipser text, Chapters 7-9
Roughly speaking, the hierarchy
Specific topics will include
Sipser text Chapter 10.2-10.3 has a brief overview; Papadimitriou has more.