Why was the Hall of a Hundred Columns unfinished when Xerxes I died?

The Hall of a Hundred Columns, also known as the Throne Hall, remained unfinished at the time of the death of Xerxes I because he was assassinated by his courtiers in 465 BCE before the project could be completed.12

While Xerxes I initiated the construction of this massive hypostyle hall as part of a lavish building program in Persepolis, he was only able to finish the paving and the base of the walls during his lifetime. The completion of the walls and the building's decoration was subsequently carried out by his successor, Artaxerxes I.12