North-west Arabia is marked by thousands of stone structures, such as ‘pendants’, tower tombs, ‘kites’, and the enigmatic monumental ‘Gates’. To date the ‘Gates’ (renamed Mustatils) have received limited attention. However, recent work in the counties of AlUla and Khaybar, Saudi Arabia, indicate these features are far more complex than previously supposed, embellished with chambers, entranceways and orthostats. These features can now be interpreted as ritual structures dating back to the late sixth millennium BC. As such, Mustatils are amongst the earliest stone monuments of Arabia and one of the oldest and most diffuse monumental building traditions known to date.