  In 1993 A. Ori \cite{Ori93} presented spacetimes violating the chronology
condition in order to answer the question whether a time machine construction
has to violate the weak energy condition or not. Later, in 2005 \cite{Ori05},
he constructed a class of time machine solutions with compact vacuum core. Both
classes include an interesting global structure and it is possible to obtain
closed timelike curves. Besides we focus on the geometric structure, in
particular symmetries and geodesics, if feasible, and visualize several
aspects.
