Final answer:
The massive entryway fortified with towers and guard rooms is called a cyclopean-walled entrance way, such as the Lion Gate. These fortifications were designed to protect the citadel sites and limit access to the main site.
Step-by-step explanation:
The massive entryway fortified with towers and guard rooms is called a cyclopean-walled entrance way. One example of such an entrance is the Lion Gate. The purpose of these fortifications was to protect the citadel sites and limit access to the main site, making it difficult for an invading army to penetrate.