On day one of leading my tour of Dakar, we were taken up into the lighthouse near where I used to live. I have always loved that place, it's the most westerly lighthouse on mainland Africa and feels completely forgotten, just an old building on a hill which despite its isolation and seeming neglect, is still functioning and essential to Dakar life.

The man working in the lighthouse, a young guy, took us all up into the tower, guided by some very well-polished brass banisters. One by one we climbed into the revolving cylinder of mirrors which reflects light from the tiniest little bulb dozens of kilometres out into the sea and across the city. Then he showed us a huge bulb, supposedly the first one used there, at the end of the 19th century, though I wonder if that's true because the glass would have had to be hand-blown. In any case, how would it have lasted 150 years of Senegalese man-handling?

Taking us out on to the terrace, our guide showed us a whole load of antennae. Some are for embassies, some for the national TV station, he said. And some, he went on, I can not tell you who they are for, because it is a secret.