Suzaku Castle

Suzaku Castle (朱雀城) is a large and (presumably) Feudal-aged castle located in Japan. In all of its appearances in the Street Fighter series, as well as crossover games, it has served as Ryu's home stage.

Description
Not much is known about the castle itself, but it can be assumed that Ryu is associated with it some way, given that it has been his home stage every time it has appeared in a game.

In Street Fighter II, Ryu's stage, set on Suzaku Castle, has signs on it reading Fūrinkazan (風林火山), a shortened version of a quote from Sun Tzu's Art of War. The same message is seen written on Ryu's belt in some of his appearances.

The Suzaku Castle reappears in Street Fighter III: 3rd Strike, where it is once again Ryu's home stage. The castle in Super Street Fighter II Turbo Revival appears exactly as it did in 3rd Strike, albeit at night. Revival also has a red-colored version which serves as Akuma's stage, as he didn't have one originally.

The castle is also in SNK vs. Capcom: The Match of the Millennium, where it is used as the background of each characters' rival battle. It is also one of the backgrounds in Street Fighter Online: Mouse Generation.

In Super Smash Bros. for Nintendo 3DS and Wii U, the stage is designed to be used in its Omega Form (a single platform for combat) rather than its normal version; the latter features a number of different platforms, including two smaller ones on the left, and two larger ones on the right.

The Suzaku Castle appears in Street Fighter V as DLC released on July 25th, 2017.

Trivia

 * According to the Street Fighter II instruction manual, the Suzaku Castle is Ryu's dojo where he lives and trains. The platform built in the outside courtyard serves as a fighting area specifically for the Street Fighter tournament. This would also serve as Ken's secondary stage since he also trained here alongside Ryu under Gouken's teachings.

Theme
Since any stage set on Suzaku Castle is associated with Ryu, any theme that plays on it is associated with him, as well (primarily the one from Street Fighter II).