You can find the Prefectural Hall right in front of Exit 5 of Nagatacho Station.
Since it's in a building right next to the subway exit, you shouldn't have any trouble finding it.
The Prefectural Hall is a building of the Public Interest Incorporated Foundation Prefectural Center, and it's used as an office and base for activities in Tokyo for 44 prefectures.
And, there's a relaxing area with seating in the plaza next to the Prefectural Hall.
▼Overall view of the rest area next to the Prefectural Hall
There are three 8-person circular stone benches and three 3-person semi-circular benches.
A distinctive feature of these benches is that they are close to the subway exit.
They're convenient for taking a break before using Nagatacho Station or for eating lunch while out and about in the Nagatacho area.
When I checked during Golden Week, there were hardly any people around the Prefectural Hall, and I had the rest area all to myself.
So, it seems that it's generally empty on weekends and holidays.
Also, these stone benches have a certain trap...
▼8-person circular stone bench
▼3-person semi-circular stone bench
There are protrusions attached to the benches to prevent you from lying down.
This is a common feature in the city center, but the protrusions are usually sloped.
I wonder if people would lie down if they were flat...
Since the Imperial Palace and its moats are nearby, it's also a good idea to use this rest area while taking a stroll around the Imperial Palace.
By the way, there is an adidas Runbase near "The rest area in the open space of Hirakawacho Mori Tower" for those who run around the Imperial Palace.
On a personal note, the manager, Pen-ta, has run around the Imperial Palace several times, and even just one lap is great exercise, so it's fun to try!
So, why not give it a try as a place to sit and relax near Nagatacho Station?