From MFA: The Tomb of Queen Helene of Adiabene, the largest tomb in Jerusalem, is located north of the Old City. It has a long, wide staircase leading down to a large courtyard (27 x 26 m.), all cut into the rock below the surrounding surface area. The facade of the tomb itself has two Ionic columns supporting an architrave adorned with carved leaves, and above it, a frieze decorated with a bunch of grapes and acanthus leaves. The entrance to the burial cave, which contains several chambers, is blocked with a large rolling stone. One of the decorated sarcophagi bears the inscription "Queen Tseddan." The tomb is ascribed to Helene, Queen of Adiabene (in the north of modern Iraq), who converted to Judaism in the first century CE and built a palace in Jerusalem. According to Josephus Flavius (Antiquities of the Jews 20: 95; The Jewish War 5: 55, 119, 147) she died in Adiabene but her remains and those of some family members were transferred for burial in the mausoleum she had built for her family in Jerusalem.
From Excavation in Jerusalem Unearths Ancient Mansion:
The Israel Antiquities Authority (IAA) announced Wednesday that the mansion it has been uncovering in Jerusalem may have been a palace belonging to Queen Helene of Adiabene. Helene built grand residences in the area of the City of David. The excavation has uncovered five-meter-high walls with stones weighing hundreds of kilograms, halls preserved to a height of at least two stories, a basement with an arched ceiling, and remnants of colored frescoes and ritual baths.