Narok is the last proper town on the road to the Masai Mara from Nairobi — about halfway, roughly 140 km out, at the top of the escarpment where the Rift Valley falls away toward the reserve. Most road safaris stop here for lunch, fuel and the last reliable ATMs and supermarket before the park. It is lined with souvenir stalls and hawkers, so expect a scrum as soon as you step out of a vehicle.
If you have time to kill before the park gates open, the Narok Museum is worth a brief stop for its coverage of Maasai culture and the broader Mara ecosystem. The central market is a livelier option, with handcrafted beadwork available at prices well below what you'll find at camp souvenir stalls.