In order to protect his property, the owner of Toplice, Zagreb's Kaptol, built a castle (fortress) next to the parish church in 1376. During the 16th century, at the time of the Ottoman threat, it was extended by towers, surrounded by a moat filled with thermal water and a chain bridge. With the cessation of the Ottoman threat, in 1695 the castle was rebuilt into a baroque castle and became the first bathing hotel. In the 18th century, the moat was buried in the 19th century. At the end of the 19th century, the facade of the Old Town was restored in the Neo-Gothic style.
In the courtyard of the castle with an impressive baroque porch there is a lapidarium - a collection of excavations of Roman stone. In the middle of the yard is a stone tub in which flowers are planted today.
Today, in the Old Town, there is the District Museum of Varaždinske Toplice, which was founded by the pharmacist and polyhistor of Toplice Josip Chabrian. Votive altars to nymphs and other deities, reliefs of nymphs from the 2nd century, plaques of Emperor Constantine the Great, are museum exhibits that testify to the uninterrupted continuity of life and medical treatment in Varazhdinske Toplice.