From central Cairo you take the ringroad towards the north of the city, towards the town of al-Marg. The road heads towards Alexandria. You get off at the junction for al-Marg (it is signposted). As you come off the sliproad the railway station for New al-Marg should be directly in front of you. So you can only go left or right. You go left and pass the railway buildings. The railway tracks will be to your right and they run parallel to the road for some distance. You go straight for about 20 minutes. The shrine is a white building on your right. Any problems - search the net for Bohri Shia organisations in Cairo, their people know the site, speak good English and are helpful. Because of other Bohri pilgrimage sites in Cairo and the fact that one of their leaders is buried outside Malik al Ashtar's shrine means that their people are the main Shia visitors here. Most importantly the locals know the site as the maqam Sheikh al Ajmi. Take a trusted driver and ask him to wait outside. There seem to be very few taxis around. My driver was a bit concerned about the place (it is a poor suburb of Cairo).