Mokrice Castle, 10km southeast of Brežice, is the loveliest fortress in the Posavje region. The castle dates from the 16th century, but there are bits and pieces going back to Roman times built into the structure. The castle is home to a hotel with an 18-hole golf course but its lovely grounds – including a 20-hectare ‘English park’ full of rare plants, a large orchard of pear trees and a small disused Gothic chapel – are open to all at no charge.
It's supposedly haunted by the ghost of the 17th-century countess Barbara, who committed suicide here after her lover failed to return from sea. She's particularly active on her name day (4 December) when she spends the night rolling cannonballs around the joint. A trip to the castle makes a lovely excursion from Brežice, especially by bike: take the secondary road from Čatež ob Savi that runs parallel to the highway.