Shikhara
Shikhara (IAST: Śikhara), a Sanskrit word translating literally to "mountain peak", refers to the rising tower in the Hindu temple architecture of North India. Shikhara over the sanctum sanctorum where the presiding deity is enshrined is the most prominent and visible part of a Hindu temple of North India.
In South India, the equivalent term for "shikhara" is "vimana".
These are not to be confused with the elaborate gateway-towers of south Indian temples, called "gopurams", which are perhaps the most prominent features of those temples.
Major styles
Among several styles of shikharas that can be seen in Hindu temple architecture, the three most common ones are:
the Dravidian style prevalent in southern India : The shikhara consists of progressively smaller storeys of pavilions. The Dravidian style is highly ornate.
the Nagara style prevalent almost everywhere else : The shikhara is beehive/curvilinear shaped.
the Vesara style, a synthesis of the two others, seen mostly in Karnataka and most commonly in Hoysala and later Chalukya temples.