Sensoji Temple is oldest and most popular temple in Tokyo and it was founded around 645 AD and enshrines a golden image of kannon.
[Asakusa temple opening hours]
Sensoji temple always opens but the main temple opens 6:00 to 17:00 (from 6:30 from October to March) and they opens 365 days. Admission is free.
There is the Kaminari-mon Gate which has a huge Japanese lantern hanging from it with the letters "雷門" and Japan's oldest shopping street Nakamise.