Piesau is a village and a former municipality in the district of Sonneberg in Thuringia, Germany, close to the Thuringian Rennsteig.

Formerly in the district Saalfeld-Rudolstadt, it is part of the town Neuhaus am Rennweg since January 2019.

Up until today glass is the main reason of existence in Piesau.

[1] The inventor of the first usable röntgenglass (Carl Heinrich Florenz Müller) descends from the village.

Piesau lies next to the "Rennsteig", a hiking path of more than 160 kilometres throughout Thüringen.