Vienna aims to be climate neutral by 2040, in part through adding photovoltaic systems, mostly on roofs. Soon the 572 solar panels installed on the roof of the Vienna City Hall will begin producing enough electricity to meet the needs of 110 households. It will save about 130 tonnes of CO2 per year. The Neo-Gothic building, built in the 1870s and 1880s during the Austro-Hungarian empire, is a cultural monument, and so the panels are not visible from the ground. Eight other public buildings in Vienna have been equipped with a solar roof and four more are in development. Currently, there are 252 photovoltaic systems with a total output of around 34 MWp on city-owned land.