Great Gates of Azulon

The Great Gates of Azulon guard the sea entrance that leads to the Fire Nation capital. A giant statue of Fire Lord Azulon stands in the middle of the water, flanked on either side by two dragon statues. When enemy ships are spotted, a net rises between the statues and ignites -- thus "closing" the gate in a wall of fire. Immediately after he took power, Azulon commissioned the gates to be built. But he couldn't decide on a name. After mulling over what to call these great gates, he finally decided to name them after himself. After all, he's the one who had the genius foresight to have these gates constructed.

During The Day of Black Sun, Part 1: The Invasion, the invasion forces approached the gates with the help of a fog cover-up made by Katara and the swamp Waterbenders, however, their arrival wasn't unnoticed, so the Fire Nation had the gate closed. When invading the oncoming invasion ships, the Fire Nation military was unable to find anyone on board due to the invasion forces using the ships as a cover-up for their submarines, effectively bypassing the gates.