If you could add a new path/road/ train line in Tokyo, where would you pick and why?

Connecting Yoyogi Park to the Takeshita Street area via an underground passage might make Harajuku station a little less of a crowded nightmare to navigate.

Also, extending the Keisei-Ueno line from Ueno to Suidobashi would also make it less of a hassle to get to the Tokyo Dome area.