Rohtas Fort is an outstanding example of early Muslim military architecture in the South Asia which incorporates features from elsewhere in the Islamic world. It also had a profound influence on the development of architectural styles in the Mughal Empire (and hence on the European colonial architecture that made abundant use of that tradition).It is also outstanding by virtue of the refinement and high artistic value of its decorative elements, notably its high- and low-relief carvings, its calligraphic inscriptions in marble and sandstone, its plaster decoration, and its glazed tiles.

And

There are no surviving examples of military architecture of this period on the same scale in the South Asia which survive to the same degree of completeness and conservation. Fatehpur Sikri (India) which is already on the World Heritage List represents the full Mughal realization of a form and style that owes everything to its precursor, Rohtas Fort.

The recommendation by ICOMOS (the organization that makes the World Heritage list) made the following recommendation

Rohtas Fort is an exceptional example of the Muslim military architecture of central and South Asia, which blends architectural and artistic traditions from Turkey and the South Asia to create the model for Mughal architecture and its subsequent refinements and adaptations.