Mashhad is considered as one of the three holy sites of Shia. Here is the sacred shrine of the eighth Imam Reza – the only burial site of a Shia imam in Iran. The name of the city’s place of martyrdom is closely linked to the tomb of Imam Reza, the eighth Imam of the Shia, who was presumably poisoned near Mashhad in 817. Today, its mausoleum attracts millions of pilgrims every year to Mashhad. Other highlights include the tombs of the famous poets Omar Khayyam and Attar Neyshabouri and the tomb of Ferdowsi, the author of the Persian national epic Shahname, the so-called Kings book.