At the base of the Taka Mountains is this spectacular mosque, centre of the Khatmiyah Sufi sect. It's a lovely mudbrick building with a pointed octagonal minaret and a photogenic arcade of columns in the main prayer hall. Non-Muslims are quite welcome to take a peek about. Afterwards have a little scramble around the bizarre peaks of the mountains. It's about 4km southeast of Kassala's centre; get there by taxi (S£20) or minibus (S£2).