At its core, Eisfeld Castle is a medieval castle complex consisting of a palace and keep, which was built in the 11th and 12th centuries on the site of an older fortification and has undergone many changes over the centuries. The bower was built in 1360 and the adjoining "New Building", which opens onto the town through a vaulted gateway, in 1580. The kitchen wing built in 1555, which closed off the building to the north-west, was replaced in 1886 by a Wilhelminian-style prison building. The simple and irregularly laid out group of buildings owes its name to the rather short princely era: inventory plans from 1680 show that the castle was intended as a temporary residence for the ducal family, at that time the Gotha dominion, to whose territory the town and office of Eisfeld belonged from 1643 to 1680 after a long affiliation to the Principality of Coburg.

The first regent of the Duchy of Saxe-Hildburghausen, which emerged from the division of an inheritance in 1680, chose Eisfeld Castle as his residence for a short time. After Duke Ernst had finally settled in Hildburghausen, the planned extension of Eisfeld Castle was not carried out. From 1728 to 1741, Duchess Sophie Albertine of Saxe-Hildburghausen chose Eisfeld Castle as her widow's residence.

The later functions of the castle, official building, residence for civil servants and official prison with the necessary conversions and extensions, have finally erased all traces of princely splendor.

The mighty walls that surround the castle on three sides are part of the city fortifications that Duke Ernst the Pious of Saxe-Gotha had built by his master builder Andreas Rudolph between 1654 and 1673 after the destruction of the Thirty Years' War. The north-eastern section of the "palace custody building" opens up inwards in seven casemates, giving the palace garden a special architectural charm. The estate, which was designed in the style of a French garden with "dainty dwarfs and trees" during the stay of the Dowager Duchess Sophie Albertine in the 18th century, later served as a kitchen garden and was only opened to the public in 1952.

Today, the castle houses a cultural hall, the registry office, the town information office and the Eisfeld Museum.