In 1994, the death of the president after his plane "crashed", sparked a genocide where an estimated 1 000 000 people were killed over a period of around 100 days. There is almost no one you meet in Rwanda that has not been adversely affected by this in some way.
Recommeded movies on the subject are: Hotel Rwanda, Shooting Dogs, 100 days, Shake Hands with the Devil, Sometimes in April and Ghosts of Rwanda.
The museum has many survivors who run the museum. Entrance is free, but a donation is asked for. Very moving and explicit. Think before you take children along. Aegis also offers free educational talks on the site regularly where survivors and perpetrators talk about the genocide.