What were some of the architectural features of the earliest stupas at Sanchi and Bharhut?

The earliest stupas at Sanchi and Bharhut had a plain architecture with stone railings. Its resemblance was like bamboo or wooden fence. The gateways were richly carved and installed at the four cardinal points. The entry of the worshippers was used to be from the eastern gateway and then they used to walk around the mound in a clockwise direction.