(Extra)  It seemed strange that there could be a house built beneath the inhospitable lava rocks on Lanzarote but surprisingly one was built within five large volcanic bubbles by Cesar Manrique.  He lived in the two storey house for twenty years after converting the bubbles into rooms which even had a swimming pool.  As a renowned artist and architect his designs were greatly influenced by the landscape and he wanted to protect Lanzarote from the modern developments that were spoiling neighbouring islands.  He tried to respect the traditions of the island and landscape and was instrumental in ensuring that buildings would be no more than the height of a tall palm tree, although there are a few exceptions.  It really was worth a visit especially with examples of his art and sculpture throughout with his large gallery explaining his work. 
The photo is one of the rooms with a tree growing up to the light.

Another spectacular and unusual house is LagOmar which was built into the side of an old quarry cliff face with a labyrinth of tunnels with steps leading into caves which have been formed as rooms and pathways leading across pools among flowers.  Inspired by Cesar Manrique, it was designed by the artist Jesus Soto and built by Sam Benady.   When the famous film star Omar Sharif was filming on the island he saw the house which was recently completed and decided to buy it.  According to legend, shortly after buying it, and knowing that he was a very keen bridge player, Sam Benady challenged him to a game of bridge with the house as the stake.  Sharif was unaware that Benady was the European bridge champion and lost the house after never having lived in it.
Both houses are very different and quite amazing.