Atlantis is an island city. It is said to be the sort of place one never wants to leave. While its Earth One counterpart is considered a "lost city" due to it seemingly being submerged in the ocean, Atlantis on Earth Two is above water.
Jay Garrick admitted to loving Atlantis, especially as one of his best friends originated there. Later, Harrison Wells opened a map of his world. A large island, presumably Atlantis, was visible west of Europe. Atlantis was a place that Barry's parents had always wanted to go, so Barry got them plane tickets to Atlantis for their anniversary.