Engaruka ruins, Lake Natron and  Odonyo Lengai:

Explore one of the oldest cities in Tanzania found at the foot of rift valley whose people built the most famous Tanzanian ruins that displayed advanced knowledge of irrigation technology.

Thereafter a drive to Lake Natron a home of huge flocks of lesser  flamingos .This gathering is one of nature’s most fantastic spectacles! 

Lake Natron is a salt and soda lake in the Arusha Region of northern Tanzania. The lake is close to the Kenyan border and is in the Gregory Rift, which is the eastern branch of the East African Rift.[1] The lake is within the Lake Natron Basin, a Ramsar Site wetland of international significance

Oldonyo Lengai: "Mountain of God" in the Maasai language, is an active volcano located in the Gregory Rift, south of Lake Natron within the Arusha Region of Tanzania. Part of the volcanic system of the East African Rift, it uniquely produces natrocarbonatite lava.  The summit of this strato-volcano is 2962 metres above sea level, and affords direct views into the caldera of Tanzania’s only officially-certified active volcano, and the world’s only carbonatite volcano; records of eruptions have been maintained since 1883, the largest of which deposited ash 100 kilometres away in Loliondo on the Kenyan border to the north west.