Complex sentence: Much land in Algiers and elsewhere in south Louisiana was owned by John McDonogh, who was one of the world's largest private land owners until his death in 1850 when his estate was willed to public schools in Baltimore and New Orleans.
Split into simpler sentences: Much land in Algiers and elsewhere in south Louisiana was owned by John McDonogh, who was one of the world's largest private land owners until his death in 1850. His estate was willed to public schools in Baltimore and New Orleans.