Territory of Peter and Paul Fortress, 2, Saint Petersburg, Russia, 197046
In front of the guardhouse, on the site of the existing lawn in the 18th century, there was a square that served as a place for punishing soldiers. There stood a "wooden horse with a sharp back," on which soldiers were seated as a penalty for several hours. Additionally, a wooden post was driven into the ground nearby, with "sharp spikes" set around it, or rather driven into the earth. The punished soldier was chained to the post and forced to stand barefoot on the spikes. For several minutes, he had to quickly move his feet, which constituted the "dance."
This is the origin of the name - Plyasovaya Square.
Sources:
L.I. Bastareva, V.I. Sidorova: PETROPAVLOVSK FORTRESS (guidebook)
Anisimov E.V. St. Petersburg in the times of Peter the Great