Following the completion of the Maidan; Abbas ordered a new building erected on the east side. The Maidan itself host Ali Qapu Palace (Fourth Building, located in the west side of the Maidan, built in 1590), Lutfallah Mosque (Built after the completion of the Maidan between 1603 & 1619), Shah Mosque (Built between 1611 & 1630) , Chahar Bagh and the bazaar  (Built on a 2 KM stretch) that connected the old city with the new Maidan. The largest square, in the north, is the Maidan-i Shah, a vast open space, with a major building complex on three sides. One of these is the Masjid-iShah, or Imam Mosque, the greatest building in a magnificent city. Its monumental gateway, with minarets 110 feet (34 Meter) high, occupies a significant pan of the southern side of the maidan.

The Lutfallah Mosque, which is dated by an inscription from 1603-1619, takes its name from Sheikh Lutfallah Maisi Al-Amili, the distinguished scholar and teacher who came to Isfahan at Abbas's request and took up 'residence on the site; the mosque was only named after him later, after his death in 1622/23. In plan, the mosque comprises a single domed room 19 x 19 meters (63 feet). The basement contains another room of almost the same dimensions, covered with low vaults resting on four octagonal piers. Since it contains a Mihrab, the domed room is aligned with the Qibla and set at an angle approx­imately 45 degrees from that of the main facade. When viewed from the Maidan, the dome is to the right of the main portal. The exterior of the dome is covered in a spiraling arabesque set against an unusual tan background. It con­trasts with the portal iwan, ablaze with blue glittering tile - most of it added in the mid-20th century during restoration under Reza Shah Pahlavi.

The portal of the Lutfallah Mosque gives access to a corridor which passes around two sides of the sanctuary, so that one enters the main room opposite the Mihrab. Emerging from such a dark, twisting corridor, the interior of the mosque is a huge contrast, for the vast, glowing room is probably the most perfectly balanced interior in all Persian architecture. In elevation, the room consists of the standard tripartite arrangement of square base, octagonal zone of transition, and dome, but the two lower stories have been integrated by arches outlined' with a cable binding executed in light blue tile and a magnificent Inscription band in white on a dark blue ground. The only other example of such vertical integration is the north dome added to the Friday Mosque in Isfahan in 1088, and Safavids architects may have taken their cues from their Seljuk predecessors. As in the earlier example, the dome of the Lutfallah Mosque is a single shell, one of the very few in Safavids architecture.

What sets the interior of the Lutfallah Mosque apart from its Seljuk prototype and from all other interiors in Safavids architecture is the exquisite tile decoration. The apex of the dome is filled with a giant sunburst, from which descend tiers of octagonal medallions filled with floral motifs, which swell in size with the -curve of the dome. Light streaming through the screened windows flickers across the glazed surfaces. The dado and some of the upper wall surfaces are riveted with tiles painted in carpet patterns; their flat surfaces are distinguished from the tile mosaics, whose uneven surfaces scatter light. The architecture and decoration are so fine that the craftsmen are credited in the inscriptions. The architect was Muhammad Riza, son of the master Hussein, the builder from Isfahan; the inscriptions were designed by the royal calligra­pher Ali Riza-yi Abbasi.

The additional function of the building is rather puzzling. In the foundation inscription over the entrance portal, it is called a mosque (Masjid), but the building lacks the standard accoutrements such as a courtyard, side galleries, iwans, or minarets. The plan fits better within the long established Iranian tradition of large domed mausoleums, but no one is known to have been buried there. Some scholars have called it a royal chapel, but this type of building is unknown in Iranian architecture and the mosque is across the Maidan from the palaces of the royal family.