Trash door. This gate was used to take trash out of the city. The Garbage, through which in the time of Ezra garbage was taken out of Jerusalem, as Nehemiah 3 14 is mentioned, leaves the exit to the Garden of Gethsemane from the Kotel Wall

“He rebuilt the gate of Muladar Mulkiah son of Rechab, governor of the province of Beth-hakerem; he rebuilt it, and lifted up its gates, its locks, and its bolts.”

Although the door is in the same place as the one Mulquias Ben Recab built, the one there is is a reconstruction made by the Ottomans BUT THE OLIVE TREES ARE MILLENNIALS, some over 2000 years old