Public works under Umar
Umar stood for simplicity and austerity. Consequently he did not believe in any large scale program of public works involving extravagance. Nevertheless as a consequence of the extension of the Muslim rule to distant lands, the undertaking of works of public utility became imperative. As Muslim conquests extended east and west, and more and more persons embraced Islam it became necessary to construct mosques. During the caliphate of Umar, as many as four thousand mosques were constructed. During the caliphate of Umar many new cities were founded. These included Kufa, Basra and Fustat. Umar issued instructions against the construction of double storied houses and palatial buildings. Many buildings were constructed for administrative purposes. Many cantonments were constructed at strategic places. Special stables were provided for cavalry.

Public works under Uthman
Under Uthman the people became economically more prosperous, and they invested their money in the construction of buildings. Many new buildings came to be constructed in Madina, and the city expanded considerably. Uthman relaxed the restriction on the construction of large houses. Uthman built a palatial building for himself known as the "Zawar". Many other Companions constructed large buildings. Intensive building activity took place at Kufa, Basra, Damascus, Fustat and other cities.

During the caliphate of Uthman as many as five thousand new mosques were constructed. Uthman enlarged, extended, and embellished the Prophet's mosque at Madina. He enlarged and extended the Holy Kaaba as well. With the expansion in army, the cantonments were extended and enlarged. More barracks were constructed for the soldiers. Stables for the cavalry were extended. Uthman provided separate pastures for State camels. During the caliphate of Uthman, guest houses were provided in main cities. More and more markets were constructed. Uthman appointed Market Officers to look after markets.

Umar had placed restriction on the purchase of agricultural lands in conquered territories. Uthman withdrew this restriction. The Arabs purchased lands in conquered territories and exchanged them with lands in Arabia. Big landed estates came to be established in Arabia, Iraq and elsewhere. In Iraq, Egypt and Persia numerous canals were dug which stimulated the process of agricultural development.

In the cities, particular attention was directed towards the provision of water supply. In Madina, a number of wells were dug to provide drinking water for the people. The water supply in Makkah was also improved. Water was brought to Kufa and Basra by canals.

Heretofore Shuaibia was the port for Makkah. It was inconvenient. Uthman selected Jeddah as the site of the new seaport. Uthman bathed in the sea-water at Jeddah, and said that it was a blessed spot. Other companions also bathed in the sea-water at Jeddah. Uthman prayed for the prosperity of the new seaport.