Sabkhat Ghuzayyil is the broad salt-flat depression south and southwest of Agedabia, usually named as the lowest point in Libya at roughly 47 metres below sea level. It is dry today, but its scale gives the coastal plain a strange, emptied-out quality.
This is not a casual excursion unless you already have desert transport and a driver who knows the tracks. The reward is not a monument but a sense of the geography that shaped Agedabia: sea to the north, salt flats and desert to the south, and long roads pulling traffic through the town.