The Horologion was constructed in the middle of the 1st century BCE. It was designed by the astronomer Andronicus of Cyrrhus in Macedonia. The structure was effectively a clock tower featuring a sundial on the exterior and a water clock inside. It is an octagonal structure with two propyla and a conical roof surmounted by a bronze weather-vane. The frieze depicted the eight wind deities with the sundial lines beneath them. The water clock inside recorded the time when the sun was not shining. In the 5th century, Christians used the Tower as a Christian church or a baptistery. Later on, the Ottomans turned it into a tekke used by the whirling dervishes of the Mevlevi Order. Finally, the building was excavated in the 19th century. To the west of the Horologion was the Gate of Athena Archegetis. It was constructed by donations from Julius Caesar (19-10 BCE) and stood on the road that connected the Roman and the classical Agora. The gate remained in use for many centuries. An equestrian statue of Lucius Caesar (Augustus’ grandson) stood at the top of the pediment.