If you're willing to brave the crazy traffic and lack of parking spaces, River Road is the place to shop for fabric and notions in Nairobi!
Years ago there were many Asian gold jewelry merchants on River Road.
It was great fun to wander from shop to shop admiring the intricate filigree work executed in 22 to 24 carat gold. Rich stuff.
The gold merchants have moved out, and the area has a poor reputation for security today, partly because it is near one of the major matatu stops in the city, and therefore draws big crowds and all kinds of people.
Generally, City Center is quite OK for a walk around, and most people on the street are friendly and helpful. Be do be alert, and it is best to avoid areas with a bad reputation like River Road.