Agra- Taj Mahal Dome

The marble dome that surmounts the tomb is the most spectacular feature. Its height of around 35 metres (115 ft) is about the same as the length of the base, and is accentuated as it sits on a cylindrical "drum" which is roughly 7 metres (23 ft) high. Because of its shape, the dome is often called an onion dome or amrud (guava dome). The top is decorated with a lotus design, which also serves to accentuate its height. The shape of the dome is emphasized by four smaller domed chattris (kiosks) placed at its corners, which replicate the onion shape of the main dome. Their columned bases open through the roof of the tomb and provide light to the interior. Tall decorative spires (guldastas) extend from edges of base walls, and provide visual emphasis to the height of the dome. The lotus motif is repeated on both the chattris and guldastas. The dome and chattris are topped by a gilded finial, which mixes traditional Persian and Hindustani decorative elements.
The main finial was originally made of gold but was replaced by a copy made of gilded bronze in the early 19th century. This feature provides a clear example of integration of traditional Persian and Hindu decorative elements. The finial is topped by a moon, a typical Islamic motif whose horns point heavenward. (Wikipedia)