Jews, Christians, and Muslims are planning to build a house of worship Berlin – the “House Of One” – that brings a synagogue, a church, and a mosque together under one roof, making it the world’s first house of prayer for three religions. The three separate sections will be linked by a communal room in the center of the building. This will serve as a meeting place, where worshippers and members of the public can come together and learn more about the religions and each other.
It is to be built in “Fischerinsel”, on the site where the first church in Berlin, St Peter’s, once stood.

There’s a crowdfunding initiative on their website. As of late 2016, about one third of the funding is already raised.