Altenburg is of course famous for its historic organ built by Henrich Gottfried Trost in 1739. But there are also organs built by Ladegast (1881 and 1906) and by Sauer (1905). In any case, Altenburg is a fantastic addition to ECHO. The Artistic Directors are Daniel Beilschmidt and Johann Friedrich Röpke.
Have a look at their city page.