First mentioned in 1208, Sonnenberg Castle was probably built by the count brothers Henry II and Ruprecht IV of Nassau around 1200 in the course of territorial disputes with the lords of Eppstein.

It consists of the late Romanesque core castle, the upper castle and the lower castle. The oldest part is the keep dating from around 1200. Four storeys rise above a barrel-vaulted dungeon, the uppermost of which again has a barrel vault. A second tower, the so-called brother tower on the attack side, is only a ruin.

At the end of the 13th century, a palas was built to the south of the core castle on a terrace around 10 m below, of which the remains of three four-storey walls still bear witness. A rectangular curtain wall surrounded this area, later known as the upper castle. A second extension took place around 1340, after which the castle ring was extended by the walled enclosure of the settlement, the so-called valley, which was elevated to town status in 1351. The walls were further strengthened at the end of the 14th century. The gate tower, also known as Bierstädter Tor, which was equipped with a drawbridge, and a massive square defense tower (also known as Kapellenturm) are still preserved today.

From 1337, Sonnenberg Castle served as the widow's seat of Irmgard von Hohenlohe for around 30 years. This period was also a heyday for the castle settlement known as "Tal": in 1351, the latter was granted town rights at Irmgard's instigation. From 1554-66, the castle once again served as a residence, after which it fell into disrepair. In 1611, it was deemed uninhabitable. On 27.08.1814, Johann Wolfgang von Goethe took a walk to Sonnenberg to spend the eve of his 65th birthday there.

In 1826, a tower room was set up on the first floor of the keep. This developed into a small local history museum, which is now run by the Sonnenberg local history association.

Sonneberg Castle was last extensively restored at the beginning of the 21st century.