The marble dome that surmounts the Taj Mahal tomb is the most spectacular feature. The top is decorated with a lotus design, which also serves to accentuate its height. The shape of the dome is emphasised 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. The finial is topped by a moon, a typical Islamic motif whose horns point heavenward. Because of its placement on the main spire, the horns of the moon and the finial point combine to create a trident shape, reminiscent of traditional Hindu symbols of Shiva. Tall decorative spires (guldastas) extend from edges of base walls, and provide visual emphasis to the height of the dome. The minarets, which are each more than 40 metres (130 ft) tall, display the designer's penchant for symmetry.