[1] It is probably the oldest surviving multi-level fully cast-iron framed building in the world, being three years earlier than the Menier Chocolate Factory in Noisiel, France, which are both amongst the few ever built.

The iron frame is composed of relatively large-scale pieces, heavier than that used on the Crystal Palace, able to support the five levels, timber and tile floors, and the infill brick walling.

The design responded to the tropical environment by placing the access on external cantilevered walkways that surround the main facades, and incorporating a large lightwell behind.

[2] The Menier Chocolate Factory in Noisiel, France, designed by architect Jules Saulnier, is often credited as the first multi-story building with a structure entirely composed of cast-iron, but it was built slightly years later, beginning in 1869, completed in 1872.

John Hudson Watson was born in 1818 in Castle Carrock, England to a farming family, but moved to London in the 1840s and established a drapery business.

[2][5] However many historians, notably author Sharada Dwivedi, dispute this legend on the basis of a lack of evidence to prove that "Tata was a man of vengeance".

[11] The building's poor structural condition has been commonly remarked, and efforts by heritage activists to persuade its present owner to invest in restoration have been unsuccessful.

[12] Just a few days after its nomination, part of the building's western façade, originally balconies developed into small offices, collapsed, killing one person and crushing several cars and motorcycles parked in the street below.

[13] No action was taken until 2019 when MHADA sought advice on restoration from a panel from IIT, wherein they observed "Repairs will be dangerous as many structural elements of the building are not rigidly connected to each other.. it will be prudent to demolish Esplanade Mansion", a decision immediately decried by heritage advocates.