Senso-ji main building. This is the oldest buddhist temple in Tokyo, and possibly the most important.
The legend says that in the year 628 a.D., two brothers fished a gold painted statue of Kannon, the goddess of mercy, out of the Sumida River, and even though they put the statue back into the river, it always returned to them.
Consequently, Senso-ji was built there for the goddess of Kannon. The temple was completed in 645, making it Tokyo's oldest temple. The Kannon statue is currently kept inside the temple, but it's not visible to the public.