Celje Castle (also known as
Celje Upper Castle or
Old Castle) (
Slovene Celjski grad,
Celjski zgornji grad or
Stari grad) is a castle ruin in
Celje,
Slovenia, formerly the seat of the
Counts of Celje. It stands on three hills to the southeast of Celje, where the river
Savinja meanders into the
Laško valley. Today, the castle is in the process of being restored. It was once the largest fortification on
Slovenian territory.