The coat-of-arms of the Brihanmumbai Mahanagarpalika (Municipal Corporation of Greater Mumbai) is prominently displayed on the facade of the BMC building. It is a four-panel shield surmounted by a heraldic lion and a blooming lotus at the base. The Sanskrit motto यतो धर्मस्ततो जय: Yato Dharmas Tato Jayaḥ (Where there is Righteousness, there shall be Victory) is inscribed in gold at the bottom.
Till the mid-nineteenth century, public buildings in Mumbai adopted architectural styles popular in Europe. Notable among them were the Neo-Classical and Gothic Revival styles. By the time Frederick W. Stevens started working in Mumbai, in 1869, a new eclectic form was gradually taking shape that incorporated European forms mixed with Indian elements inspired by Hindu and Islamic architecture. This new style came to be known as Indo-Saracenic.
Bartle Frere had envisioned Mumbai as urbs primus in Indis as early as the 1840s, when he collaborated with architect Henry Conybeare for building the Afghan Church at Navy Nagar, Colaba. His vision of Mumbai as India's prime city set in motion the Gothic Revival phase, which reached its peak under his patronage and in the last decades of the nineteenth century.
Though they are mistaken as lions, the 'lions' at the BMC building are chimeras—a mix of various animals—hence they appear with wings and a serpentine tail. The chimera has been attributed to the British dominance over land, sea, and air. However, it is more likely that the motif was inspired by the flag of the Republic of Venice, which featured winged lions, one of the many elements Frederick W. Stevens incorporated from Venetian Gothic architecture.
The foundation stone for the BMC building was laid on December 19, 1884, by the Viceroy, the Marquis of Ripon. The commemorative plaque can be seen inside the BMC building at the entrance lobby. However, work on the site started five years later, on April 25, 1889. After four years of construction, the BMC building was finally completed on July 31, 1893.
FW Stevens submitted two colored drawings of his design, one of its exterior and one of the Council Chamber, backing it with convincing arguments. He had visited Europe to study town halls and proposed a well-ventilated building for the municipality. Steven's new design was accepted and he was awarded the project, and Chisholm's proposal was canceled.
Commemorative plaque dedicated to Frederick W. Stevens as the designer and superintendent of the Municipal Buildings. Below Stevens is his assistant and resident engineer, Rao Sahib Sitaram Khanderao, who would later design (with DN Mirza) the Taj Mahal Palace Hotel. Also mentioned is Grattan Geary, who was the President of the Corporation and a friend of Stevens. Stevens had designed Geary's private villa at Lonavala.
Frederick W. Stevens used allegorical figures to represent concepts like progress and prosperity. This, for example, is a Christian motif of a winged angel holding up a miniature ship to highlight Mumbai's association with maritime trade. The allegoric figure represented is urbs primus in Indis (Latin for the ‘primary urban city of India’), which was adapted as the motto of the Brihanmumbai Municipal Corporation.
CSMT and the BMC building were among the first in Mumbai to use cantilevered staircases. The stairs were instead embedded in the wall at one end, with the other end 'free'. Sitaram Khanderao, who assisted Stevens on the BMC building, would go on to use cantilevered stairs for the Taj Mahal Palace Hotel, which he designed in collaboration with D.N. Mirza.
Though externally the BMC building has largely retained Frederick Steven's original design, the interiors have periodically been modified to cater to political and nationalistic compulsions after the end of British rule. Here, for example, portraits of Jyotirao Phule, Chhatrapati Shivaji Maharaj and Dr B.R. Ambedkar have been added over doorways.