A riwaq (or rivaq, Arabic: رواق) is an arcade or portico open on at least one side. It is an architectural design element in Islamic architecture and Islamic garden design.
A riwaq often serves as the transition space between interior and outdoor spaces. As portico or arcade structure, it provides shade and adjustment to sunlight in hot climates, and cover from rain in any locale.
As an arcade element the structure is often found surrounding and defining the courtyards of mosques and madrasahs, and used for covered circulation, meeting and rest, and ritual circumambulation. the arcade element is also found along principal walkways of larger bazaars.
Riwaq arcade examples include:
Surrounding the Kaaba in the Masjid al-Haram mosque courtyard in Mecca, and the Mosque of Uqba courtyard in Tunisia.
Along the main avenues of the Bazaar of Kashan, in present day Iran.
Source From Wikipedia