Yahya Arhab / EPA
The Dar al-Hajar (Rock Palace) is perched atop a rock pinnacle at the Wadi Dhahr Valley, north of the capital Sana'a, Yemen, on 09 August 2011. The historical five-storey palace was built by Yemen's ruler Imam Mansour Ali Bin Mehdi Abbas in 1786 AD. In the 1930s, the late Yemeni monarch Imam Yahya Hameed Al-Din added the upper story and annexes and used it as his summer residence.
What an extraordinary piece of architecture.