Dar Al-Hajar ('Abode of Rock', 'House of Stone'), is located in Wadi Dhahr, about 14km (9 miles) northwest of Sana'a. Situated on a rocky outcrop near the centre of the valley, Dar al-Hajar - the 'Rock Palace; - was a summer retreat for the hereditary imams of Yemen, dating back at least as far as 1786, when it was built on the instructions of Imam Mansour Ali Bin Mehdi Abbas. Although there are indications that the site may have been inhabited for many centuries, Dar al-Hajar in its present form dates from the reign of Imam Yahya in the 1930s. Standing five stories tall, it is open to the public and houses a small museum.