The knight is always guarding the facility, and making sure no one escapes. Except does not let trespassers enter at all costs.

Foundation Files: SCP-3161 refers to a man-made subterranean tunnel system discovered beneath the countryside of Shropshire, England, consisting of a network of walkways and arches carved out of sandstone. Architecture places construction between 100 BC and 50 AD. At the time of writing, 2600 m2 of SCP-3161 have been explored. However, it is speculated to cover approximately 3000+ m2. The sediment making up SCP-3161, as well as that of the surrounding area, is impenetrable. There is no significant sign of degradation from age or use.

Guarding the entrance and interior of SCP-3161 is an animate human skeleton, adorned in a full set of 15th century English armor, and equipped with a broadsword, halberd, and wooden shield. This entity has been designated SCP-3161-1.

Despite complete lack of vital internal organs, SCP-3161-1 is capable of speech, movement, and sentience. SCP-3161-1 has also demonstrated capability of detachment and reattachment of any singular portion of its composition. Removed portions remain capable of motion independent of SCP-3161-1. However, SCP-3161-1 posses little physical strength and durability. Armor and equipment carried by SCP-3161-1 encumbers it, causing the subject to move slowly. In moments of aggression, SCP-3161-1 displays difficulty in attacking effectively.

Upon initial discovery, SCP-3161-1 was observed to be hostile toward all personnel within SCP-3161, vocalizing threats in what was determined to be Middle English. SCP-3161-1 has since become docile, as an ongoing process has begun to facilitate communication with the entity.