The Sanja Festival, which takes place in Asakusa every May, is one of the most energetic and crowded festivals in Tokyo. With almost two million attendees, the streets quickly become filled with visitors hoping to catch a glimpse of the mikoshi (portable shrines) being carried throughout Asakusa. As with every festival in Japan, there are dozens of food stalls set up selling traditional fair food like yakisoba, chocolate bananas and okonomiyaki.
Sanja Matsuri is one of Tokyo's biggest festivals and features over 100 mikoshi floats paraded through the grounds of Senso-ji..
The area in and around the Senso-ji Temple grounds are absolutely packed. Not only are there tons of people, but attendees often stop and gawk as the mikoshi passing by, causing foot traffic to come to a complete halt. I recommend exploring the side streets near Senso-ji during the three-day festival. Mikoshi are still carried in and around the outer areas, with the participants screaming chants and playing instruments, but you get to view the mikoshi without the crowds and get a better opportunity for photos.
Find out more about Sensoji Temple.