The foremost reason to go to Granada is to visit the magnificent Alhambra and Generalife. The complex of palaces, fortress and gardens (built between the 13th and 15th centuries by the Nasrid dynasty) is a must-see. Plan to spend the better part of a day touring it. During warmer months, the palaces are open at night. Although you won't be able to see the architectural ornamentation as clearly, the atmosphere is incredible and there are fewer visitors then. Viewing the Court of the Myrtles and the Court of the Lions by moonlight is something you'll remember for the rest of your life.
Admission to the Alhambra is limited to protect the monument, and it is so popular that lines of up to two hours are not uncommon in high season. It is recommended that you purchase a timed-entry ticket in advance to ensure admission to the complex. For more information, visit http://www.alhambratickets.com.
Like the Alhambra, the district of the Albayzin, built on the hill opposite the Alhambra, is also a UNESCO World Heritage Site. The medieval, whitewashed quarter's architectural highlights include El Banuelo (an 11th-century bathhouse), the Palacio of Dar al-Horra and the patio of the former main mosque of the Albayzin (preserved as part of the Iglesia del Salvador). There are also several boutique hotels in converted courtyard houses, as well as a good variety of restaurants, bars and teterias (teahouses). The view of the Alhambra and the Sierra Nevada Mountains from the Mirador de San Nicolas is alone worth a trip to the Albayzin.
The cathedral stands on what is today the heart of the old city. The large complex, built where the city's former main mosque once stood, includes the Capilla Real (where Ferdinand and Isabella are interred) and the Church of the Sagrario. Nearby, narrow streets attempt to re-create the old Arab bazaar—mostly souvenir shops there. If you look east, an ornate, monumental portal is likely to catch your eye. It belonged to a 14th-century inn for traveling merchants, referred to today as the Corral del Carbon. To the south is the Bib-Rambla square, a nice spot to have a drink or dine at an outdoor restaurant. The main shopping streets are just beyond the square.
If you're spending more than two days in Granada, other sightseeing options include the baroque Cartuja monastery, and the church and monastery of San Jeronimo. Fans of the poet and playwright Federico Garcia Lorca can visit his family's country home, Huerta de San Vicente, which is located in a park named for him. Also, if you're there during the winter, you can ski the slopes at the Sierra Nevada ski station, which is about 20 mi/35 km from Granada. During the summer, hikers will enjoy the Alpujarras region on the southern slope of the Sierra Nevada range. Granada is 225 mi/360 km south of Madrid.