By the latter-half of the 18th century Edinburgh had established itself as an Enlightenment city and there was a push for it to look as such to reflect its ulta modernity. The neoclassical suburb of New Town began its constructed in 1765, allowing well-to-do residents an opportunity to get out of the crowded medieval area of the city and establish themselves in new fashionable digs. This meant there was a new fashion-capital of the town, and an old assembly room would no longer appeal to the targeted clientele; a new, thoroughly modern assembly room must be erected.
Just as with the New Town's plans, a competition was held for the design of the new Assembly Rooms and it was won by John Henderson. The cost of construction was £6,300 and came from a public subscription. By 1787 the rooms were finished and could boast being the largest in the country, even surpassing Bath's famous pump room. Finally, Edinburgh residents felt as though they could rival the entertainments found in the south with the splendor of venues like the Assembly Rooms. This however, put a bit of pressure on Edinburgh society to maintain this distinction and in 1818 (arguably the height of assembly room entertainment) a grand portico was added because it was thought the building was lacking in splendor.
The Assembly Rooms, much like the rival Bath assembly rooms, still stand today. After undergoing a recent refurbishment they are now back to the glittering splendor that so impressed guests in 1787.