Part fortress (the Alcazaba), part palace, part garden (the Generalife) and part government city (the Medina), this medieval complex overlooking Granada is often considered on par with the 7 wonders of the world. Many visitors come to Granada expressly to see the Alhambra.
The Alhambra was a palace, a citadel, fortress, and the home of the Nasrid sultans, high government officials, servants of the court and elite soldiers (from the 13th to the 14th century). Other notable buildings belonging to a different time period are also included, such as the Renaissance style Palace of Charles V, which houses the Alhambra Museum (most of the items are from the site of the monument) and the Fine Art Museum.
In order to fully appreciate the unique architecture of the Alhambra set within the surrounding landscape, it is advisable to visit an area of the Albaicín called the Mirador de San Nicolás, or go to Sacromonte. From both of these places the Alhambra's spectacular location, lying just above the city of Granada, can really be admired.
Highly recommend you book tickets to the Alhambra in advance, as the number of visitors allowed is limited and tickets tend to sell out. These can be booked online, by phone (902 22 44 60 within Spain, 00 34 91 537 91 78 from outside), or in person at branches of the BBVA bank. Several hundred tickets are reserved for sale on the day but these usually require arriving early and queueing for an hour or two. The Bono card can be still available after the regular tickets have sold out. Failing that, quite a lot of the site is accessible without a ticket. This general caution applies to cruise ship land tours (e.g., from Malaga); failure to book Alhambra tours early (before or during cruise) may mean no tours/"busses" are available.
Note that visiting hours are split into 3 periods: morning, afternoon, and evening. Tickets are issued for a specific period and access to monuments will not be granted outside those hours. However, once inside visitors may remain until closing time. In addition, each ticket is scheduled for access to the Nasrid Palaces for only a 1/2-hour time window (shown on the ticket) within your visiting period.