Create an image of an ancient underwater city filled with advanced technology, where ancient robots guard the secrets of a lost civilization.

Visualize an ancient city submerged underwater, surrounded by echoey mystery and filled with ultra-modern technology. Dilapidated stone buildings, covered in moss and coral, stand tall amidst the swirling currents. However, they are interrupted by high-tech structures glowing with neon lights and bustling with activity. Ancient robots, showing signs of rust but still operational, are stationed in key areas, guarding the hidden secrets and relics of a civilization that has long vanished from the earth. These robotic sentinels, as silent as the ocean depths, provide a stark contrast to the surrounding otherworldly serenity.