Falak-ol-Aflak is located near a river and dates back to the Sassanid era, the Tehran-based English newspaper 'Iran Daily' reported.
The ancient castle draws thousands of tourists every year.
Ata Hassanpour, an archeologist from Lorestan, said the castle has been renovated several times.
Also, Director General of Lorestan Cultural Heritage, Handicrafts and Tourism Department Gholam Reza Soleimani said that $2 million will be required to complete the process of fortifying Falak-ol-Aflak Castle.
Over 30 percent of the castle has been fortified, he added.
In related news, Lorestan Governor General Houshang Bazvand said $6.6 million would be allocated for demarcating the precincts of Falak-ol-Aflak Castle, of which $3.6 million has been earmarked.
Deputy head of Cultural Heritage, Handicrafts, and Tourism Organization of Iran during a visit to Khorramabad last May said the precincts of Falak-ol-Aflak Castle would be completely demarcated by March.
Saeed Shirkavand added that CHHTOI seeks to resolve the problems pertaining to the buildings within the precincts of Falak-ol-Aflak Castle.
Meanwhile, Head of Falak-ol-Aflak Cultural Heritage Base Ahmad Nasrollahi said the fortification of Falak-ol-Aflak Castle would be completed within 18 months once the funds are made available.
Spread over an area of 5,300 sqm, Falak-ol-Aflak Castle has eight circular towers and very solid walls.
In view of its unique architectural style, the fortress hosts one of the most prestigious anthropology museums of Iran.
It is regarded as one of the most important tourism attractions of Khorramabad.
The anthropology museum of Falak-ol-Aflak provides visitors an opportunity to become familiar with the rituals of ethnic groups, as well as showcase the living conditions of the residents of Lorestan.