Who is buried here
The mausoleum stands within the grounds of the former palace and commemorates three people whose lives bracket the end of the Rwandan monarchy.
King Mutara III Rudahigwa — Rwanda's first Christian monarch, the driver of its modernisation, and the man who built both the Western-style palace at the King's Palace site and the unfinished one at Rwesero. He died in 1959.
King Kigeli V Ndahindurwa, his brother, who succeeded him and reigned very briefly before going into exile. The monarchy was abolished shortly afterwards.
Queen Rosalie Gicanda, Mutara III's widow, who remained in Nyanza after the monarchy ended and lived quietly in the town for decades. She was killed in the 1994 genocide against the Tutsi. Her presence here is what turns the site from a royal cemetery into something else — the whole arc of twentieth-century Rwanda ends on this one hill.
Visiting
Around an hour, and quiet. The guiding covers the reigns and the pressures the last two kings governed under, which is the part most visitors have no framework for — the transition from monarchy to republic is far less well known outside Rwanda than what came later.
Where it fits
Mwima is a stop on the Royal Trail and is close enough to the King's Palace to walk. Do it after the King's Palace Museum — the palace gives you the court, the mausoleum gives you the ending. See Nyanza for how to build the day.