The great mosque founded by al-Walid in Damascus, later known as the Umayyad Mosque, became one of his greatest architectural achievements.
Under his predecessors, Muslim residents had worshipped in a small muṣallā (Muslim prayer room) attached to the 4th-century cathedral of John the Baptist, itself a successor to the temples of Hadad and then Jupiter.
However, by the time of al-Walid's reign, the muṣallā could not cope with the fast-growing Muslim community and no sufficient free spaces were available elsewhere in the urban space of Damascus for a large congregational mosque.
Thus, in 705, al-Walid had the church converted into a mosque, compensating local Christians with other properties in the city.
Most of the structure was demolished, with the exceptions of the exterior walls and corner towers, which were thenceforth covered by marble inlays and mosaics.
The caliph's architects replaced the demolished space with a large prayer hall and a courtyard bordered on all sides by a closed portico with double arcades.
A large cupola was installed at the center of the prayer hall and a high minaret was erected on the mosque's northern wall.
The mosque was completed in 711 and Blankinship notes that the field army of Damascus, numbering some 45,000 soldiers, were taxed a quarter of their salaries for nine years to pay for its construction.
The scale and grandeur of the great mosque made it a "symbol of the political supremacy and moral prestige of Islam", according to historian Nikita Elisséeff.
Noting al-Walid's awareness of architecture's propaganda value, historian Robert Hillenbrand calls the Damascus mosque a "victory monument" intended as a "visible statement of Muslim supremacy and permanence".
The mosque has maintained its original form until the present day.

In Jerusalem, al-Walid continued his father's works on the Haram al-Sharif (Temple Mount).
A number of medieval-era Muslim accounts credit the construction of the al-Aqsa Mosque to al-Walid, while others credit his father.
Furthermore, it is likely that the currently unfinished administrative and residential structures that were built opposite the southern and eastern walls of the Haram, next to the mosque, date to the era of al-Walid, who died before they could be completed and were not finished by his successors.

In 706/707, al-Walid instructed Umar ibn Abd al-Aziz to significantly enlarge the Prophet's Mosque in Medina.
Its redevelopment entailed the demolition of the living quarters of Muhammad's wives and the expansion of the structure to incorporate the graves of Muhammad and the first two caliphs, Abu Bakr (r. 632–634) and Umar ibn al-Khattab.
The vocal opposition to the demolition of Muhammad's home from local religious circles was dismissed by the caliph.
An ornate enclosure was built around the graves and fitted with a concave miḥrāb (prayer niche), four minarets and a pentagonal-shaped entrance.
Al-Walid lavished large sums for the mosque's reconstruction and supplied Umar with mosaics and Greek and Coptic craftsmen.
According to Hillenbrand, the building of a large scale mosque in Medina, the original center of the Caliphate, was an "acknowledgement" by al-Walid of "his own roots and those of Islam itself" and possibly an attempt to appease Medinese resentment at the loss of their city's political importance to Syria under the Umayyads.
Other mosques that al-Walid is credited for expanding in the Hejaz include the Sanctuary Mosque around the Ka'aba in Mecca and the mosque of Ta'if.
The great mosque founded by al-Walid in Damascus, later known as the Umayyad Mosque, became one of his greatest architectural achievements. Under his predecessors, Muslim residents had worshipped in a small muṣallā (Muslim prayer room) attached to the 4th-century cathedral of John the Baptist, itself a successor to the temples of Hadad and then Jupiter. However, by the time of al-Walid's reign, the muṣallā could not cope with the fast-growing Muslim community and no sufficient free spaces were available elsewhere in the urban space of Damascus for a large congregational mosque. Thus, in 705, al-Walid had the church converted into a mosque, compensating local Christians with other properties in the city. Most of the structure was demolished, with the exceptions of the exterior walls and corner towers, which were thenceforth covered by marble inlays and mosaics. The caliph's architects replaced the demolished space with a large prayer hall and a courtyard bordered on all sides by a closed portico with double arcades. A large cupola was installed at the center of the prayer hall and a high minaret was erected on the mosque's northern wall. The mosque was completed in 711 and Blankinship notes that the field army of Damascus, numbering some 45,000 soldiers, were taxed a quarter of their salaries for nine years to pay for its construction. The scale and grandeur of the great mosque made it a "symbol of the political supremacy and moral prestige of Islam", according to historian Nikita Elisséeff. Noting al-Walid's awareness of architecture's propaganda value, historian Robert Hillenbrand calls the Damascus mosque a "victory monument" intended as a "visible statement of Muslim supremacy and permanence". The mosque has maintained its original form until the present day.
In Jerusalem, al-Walid continued his father's works on the Haram al-Sharif (Temple Mount). A number of medieval-era Muslim accounts credit the construction of the al-Aqsa Mosque to al-Walid, while others credit his father. Furthermore, it is likely that the currently unfinished administrative and residential structures that were built opposite the southern and eastern walls of the Haram, next to the mosque, date to the era of al-Walid, who died before they could be completed and were not finished by his successors. 
In 706/707, al-Walid instructed Umar ibn Abd al-Aziz to significantly enlarge the Prophet's Mosque in Medina. Its redevelopment entailed the demolition of the living quarters of Muhammad's wives and the expansion of the structure to incorporate the graves of Muhammad and the first two caliphs, Abu Bakr (r. 632–634) and Umar ibn al-Khattab. The vocal opposition to the demolition of Muhammad's home from local religious circles was dismissed by the caliph. An ornate enclosure was built around the graves and fitted with a concave miḥrāb (prayer niche), four minarets and a pentagonal-shaped entrance. Al-Walid lavished large sums for the mosque's reconstruction and supplied Umar with mosaics and Greek and Coptic craftsmen. According to Hillenbrand, the building of a large scale mosque in Medina, the original center of the Caliphate, was an "acknowledgement" by al-Walid of "his own roots and those of Islam itself" and possibly an attempt to appease Medinese resentment at the loss of their city's political importance to Syria under the Umayyads. Other mosques that al-Walid is credited for expanding in the Hejaz include the Sanctuary Mosque around the Ka'aba in Mecca and the mosque of Ta'if.
Al-Walid I