The image clearly shows the Imperial Palace. Many photos have been taken of the palace but the Emperor doesn't (appear to) tweet much. The Imperial Palace is open to the public two days a year: December 23rd (Emperor's Birthday) and January 2nd. Limited tours are also conducted throughout the year.
The lines in the image are train lines . The dots are the neighborhoods around stations. The massive dots are Shinjuku, Shibuya and Ikebukuro.
The Imperial Palace is the center of Tokyo.