This is Hambach Castle in Neustadt an der Weinstraße. In 1832, the „Hambacher Fest“ took place there, a huge public gathering in support of civil rights and a free press.
Probably the democratic German tricolor black-red-golden was raised there for the first time. As also French and Polish activists participated and spoke, the event rooted German democracy in a European context.
Lightning this monument in blue and yellow these days seems very appropriate to me. Einigkeit und Recht und Freiheit. Slava Ukraini.