Both buildings share a similar symmetrical design, central doorway and top floor decorated with Thomson’s signature Greek columns.

The Grosvenor was the first to be constructed in 1861, ahead of the Egyptian Halls in 1872. It was renovated in 1864 after a fire, a year before the Grecian Chambers was completed. Such was the demand for office space that an additional layer was added to the top of the building in 1907; the original height can be judged by the smaller building to its left. The new architect, James Hoey Craigie, made some effort was made to match the original design with elongated Greek columns holding up the baroque restaurant extension, although the twin domes at either side seem odd and out of place. The interior has been extensively remodelled to attract businesses to the luxury offices now found within the old walls.