The district of Kondoa, especially around the tiny village of Kolo, lies at the centre of one of the most impressive collections of ancient rock art on the African continent. The overhanging rocks in the surrounding hills shelter two thousand years' worth of artistic expression, with some sites being still actively in use for animist worship. It's one of Tanzania's least-known and most underrated attractions and, if you can tolerate a bit of rugged travel, makes an intriguing and worthwhile detour.
To visit independently, stop at the Antiquities Department Office along Kolo’s main road to arrange a permit (Tsh27,000/13,000 per adult/child) and mandatory guide (free, but tips expected), some of whom speak English. There’s a good little museum here covering not only archaeology, but also the culture of the Irangi people.