This substantial limestone structure measures 5.2 metres from northeast to southwest and 3.5 metres from northwest to southeast, projecting boldly outward from the castle’s defensive walls. Its most striking feature is the complete outer arch, a rounded masterpiece of medieval masonry standing 3.3 metres high and 2.3 metres wide, with limestone blocks carefully dressed using diagonal tooling techniques that showcase the skill of its builders.

The gatehouse’s defensive capabilities are evident in its design, particularly in the portcullis niche carved into the outer pier, which once housed the mechanism for a heavy iron gate that could be dropped to seal the entrance in times of danger. Though the upper floor of the gatehouse has long since crumbled away, historical evidence suggests it was once accessible via a pointed doorway from the keep’s first floor immediately to the north, creating an interconnected defensive system that allowed guards to move freely between structures.

The strategic placement of the gatehouse also provided access to the first floor of the castle’s great hall to the south, demonstrating how medieval castle design prioritised both defence and practicality. This careful integration of the gatehouse with the keep and hall reveals the sophisticated planning that went into Rindown Castle’s construction, creating a fortification that balanced military strength with the needs of daily castle life. Today, visitors approaching from the northwest can still appreciate the gatehouse’s commanding presence and imagine the countless travellers, soldiers, and nobles who once passed beneath its weathered arch.