“Hokoten” translates literally as “Walker’s Paradise”, and it refers to the practice of (temporarily) switching a roadway from vehicular use to pedestrian use, usually during lunch hour, weekends, or special events.

Currently, there are three major weekly Hokoten in Tokyo (the following facts & figures come from the Tokyo Metropolitan Police):

Akihabara:

• ~570 meters (~1,870 feet) of Chuo-dori (highlighted below in red).
• Sundays
• April – September:  1 pm – 6 pm
• October – March:  1 pm – 5 pm

Ginza:

• Approximately 1,100 meters (~3,610 feet) of Chuo-dori (highlighted below in red).
• Saturdays, Sundays, holidays
• April – September:  noon – 6 pm
• October – March:  noon – 5 pm

Shinjuku (新宿3丁目):

• An area of ~30 city blocks on the NE side of Shinjuku Station, the main trunk of which is approximately 730 meters (~2,400 feet).
• Sundays & holidays
• April – September:  noon – 6 pm
• October – March:  noon – 5 pm

Additionally, there are lunch-time Hokoten such as in Kagurazaka, and since 2016, a very large area in Shibuya (~50 city blocks) has been Hokoten-ized for the New Year’s countdown:

Here is the Hokoten area for the Azabu Juban Noryo Festival:

Last but not least, many many commercial streets all across Tokyo become de-facto Hokoten every night, as can be seen (for example) in these two walk-through videos of Shibuya (especially Udagawa-cho):

In the above video from Rambalac, Hokoten areas are shown from 5:42 to 8:54 (Center Street), and from 15:40 to 18:51 (Mark City area).