General Characteristic of Islamic Architecture

1. Domes

The Dome of the Rock in Jerusalem which closes resembles the Church of the Holy Sepulchre, shows strong Byzantine influence. For example, both domes feature tiles laid against a gold background, vaulted interior spaces, decorative arabesque patterns and a circular dome.

2. Minarets

The minaret, or tower, is an Islamic architectural feature that comprises a tall spire with a conical crown. The basic minaret structure includes a base, shaft and gallery. The minaret serves the purpose of providing a visual focal point from which the call to prayer is made. The Great Mosque of Kairouan in Tunisa is one of the oldest standing examples of the minaret.  

3. Arab-Plan or Hypostyle

The hypostyle used in Islamic Architecture was one of the earliest styles pioneered under the Umayyad Dynasty. The mosques were characterized by square or rectangular plans that included a covered prayer hall and enclosed courtyard. The hypostyle Islamic architectural style can be seen in the example of the Mezquita in Cordoba, Spain. The building has over 850 columns made of granite, jasper, onyx and marble.

4. Sehan (Courtyard)

1. • The Sehan is a typical Islamic architectural characteristic featured in almost every mosque. It is also seen in traditionally constructed buildings and residences in the Arab world. When the courtyard is attached to a mosque it is used for the performing of ablutions prior to entering the mosque.

Reference: 
http://www.ehow.com/info_8509956_characteristics-islamic-architecture.html
http://www.bbc.co.uk/religion/religions/islam/art/architecture.shtml(1) Grube, E. J - What is Islamic Architecture?, in Michell, G., editor, - Architecture of the Islamic World: its history and social meaning, London, 1978

Image:
http://atheism.about.com/library/FAQs/christian/blxtn_jerusalem-dome10.htm
http://americanvision.org/3820/why-dome-of-the-rock-is-better-than-a-rebuilt-temple/
http://www.beautifulmosque.com/mosque-of-uqba-in-kairouan-tunisia/
http://www.onephotoeveryday.com/?p=727
http://en.wikipedia.org/wiki/Mosque–Cathedral_of_Córdoba
http://commons.wikimedia.org/wiki/File:Mezquita_de_Córdoba_Mihrab.jpg
http://www.coulouris.net/george-jean/Egypt2001/khan/Al-Azhar%20mosque8-pp.JPG