29th January - The angry clouds of the night before had gone, leaving behind a few thin whisps which would soon be burnt off by the sun. Close to our camp we found an excellent example of an old birka (unfortunately close to a pool of stinking waste water). When the wadi was in flood, the water would enter the first chamber (in the foreground of the photograph to the right) and then filter into a second chamber up to 30 metres deep.

Further up the wadi we hit tarmac and entered Dhabia - what had been a quiet village when Abdullah had visited a few years before was now a sprawling mass of concrete. Not wishing to stay too long we paid a quick visit to the governor, located the birka we were hunting for (in between a scrap heap and a field of oilseed rape) and sped back into the desert and on to Hafr al Batin, the last big town before the border. In Shakespear's day this would have been just a collection of wells - the town had now engulfed the wells and old buildings. But with a bit of detective work we were able to locate the wells - most covered by roads, but easy to spot because of the dip where the tarmac slowly sinks into the well - Richard felt more than a little self-conscious taking photographs of different coloured patches of tar!

Following the road out of Hafr we rejoined the desert - now very flat and with a greenish tinge - judging by the numbers of camel and goat herds we could see, this was a good grazing area!

Back in the Batin we spent the next two hour racing around the desert in search of Kasr Bilal - according to Shakespear, a castle with a story. Apparently the Sheikh of the Bani Hilal had a favourite slave named Bilal. This slave amassed a great wealth in camels and went on to become very influential, eventually building he castle that we were hunting. Sadly, according to the Bedu questioned by Abdullah, our search was in vain - the castle had been demolished some years before.

And so, our last night in Saudi Arabia - and to commemorate the occasion, I cooked a giant vat of chicken curry - we really know how to live.