Sanja Matsuri is a festival held in Asakusa every year in May. It celebrates the three people involved in the creation of Senso-ji and later enshrined as Shinto kami in Asakusa Shrine, next to the temple. It is one of the biggest festivals in Tokyo, with about 100 mikoshi (portable shrines) paraded around the neighbourhood.
The Asakusa Culture Tourist Information Center is a modern building located in front of the Kaminarimon Gate of Senso-ji, in Asakusa. The top floor has a cafe, as well as a freely accessible observatory with a great view on Senso-ji and Tokyo Skytree.
In May, starting at Kameido station, I walked east towards Edogawa City, until I reached the Arakawa River. I then crossed it in order to visit Funabori Tower Hall and its observatory. I went back to the other side of the Arakawa and walked along the Kyu-Nakagawa River (旧中川) then turned west at the Kitajukken River (北十間川), which goes all the way to the Sumida River, passing in front of the Tokyo Skytree. I ended the day with the Sanja Matsuri in Asakusa.
Asakusa has a large number of shrines and temples in easy walking distance from each other. There is even a pilgrimage of the 7 Lucky Gods, where you can go through a few of those shrines and collect stamps along the way. For myself, I did my own pilgrimage last April. Starting in Uguisudani, the least used station of the JR Yamanote line and finishing at Senso-ji, I visited:
On Saturday, I went to Senso-ji Temple in Asakusa to watch a nakizumo ceremony. During the event, babies held by sumo wrestlers face each other in a mock sumo game, two at a time. A referee shouts “Nake, Nake” (“Cry, Cry”) at them and the baby who then cries the loudest is declared the winner. If no baby cries inside of 1 minute, referees will use demon masks to try to scare the babies. The ceremony is religious and has its root in the belief that crying brings good health to the babies and scares evil spirits. It has been going on for 400 years and there are similar events (with different rules) in many places in Japan. I took a few pictures but my zoom is not very powerful. This page has more close-up shots of the event.
Sumida Park straddles both sides of the Sumida River near Senso-ji Temple in Asakusa. It contains a large number of cherry trees that make it a very popular spot during cherry blossom season. I went there after Ueno Park, since it is quite close.