Now: Stately streets and alleys lined with historic brick buildings - high end art, antique, and furnishing dealers are the primary tenants now, supplemented by agencies and architecture firms. The area is never bustling, unless you count Bix and a couple of other dining/drinking spots at night.
Then: Jackson Square has history that you would hardly believe from walking through the area today. The city's east shoreline originally ended at about Battery Street, so this area, along with Broadway in North Beach, was the front line known as the Barbary Coast. When sailors stepped off their vessels, this was where they were simultaneously served and taken advantage of.
How To Get There: Jackson Square is a walking destination, and it's easy to go that way from the Financial District on Sansome Street, from Justin Herman Park and Embarcadero by Washington Street, or from North Beach at Pacific Avenue.

International Settlement Towers, at Pacific and Montgomery

Kartell US Furniture on Pacific Avenue near Montgomery

Barbary Coast Trail sidewalk plaque

Bix - American dining, on Gold Street, just north of Jackson Street, between Montgomery and Sansome

Hedge Gallery and Furniture Sales on Gold Street

Balance Street, between Jackson and Gold, in Jackson Square

Zinnia - American cuisine on Jackson near Montgomery

Peter Pap Oriental Rugs on Jackson Street

Lebreton Antiques Gallery on Jackson Street

Old Ship Saloon on Pacific at Battery

Hippodrome Building on Pacific Avenue

Jack Morton Worldwide, on Pacific Avenue

Montgomery Gallery

Bocadillos - Spanish, Tapas, on Montgomery Street, just north of Columbus

Amadi Carpets

Chappel and McCullar on Jackson Street

US Custom House Building on Battery Street

Digital Revolution Printing Services, on Jackson at Battery

Entrance to Sydney G. Walton Square Park in Jackson Square

Fountain in Walton Square Park

Inside Walton Square Park

Tiled tower in Walton Square Park

Residential homes overlooking Sydney G. Walton Square Park in Jackson Square

Buildings to the south of Sydney G. Walton Square Park

Pacific Avenue Mall, at the corner of Walton Square Park

Kokkari - Greek cuisine on Jackson Street at Front Street, across from Sydney G. Walton Square Park

Globe - American dining on Pacific Avenue at Battery