Now: Thick with workers and business people at all hours of the weekday, the financial district turns majestic and desolate on weekends, as the tall buildings cast giant lonely shadows across the sidewalks. If you're at leisure here on a weekday, you have a crazy number of lunch spots available to you, along the street level of the high buildings.
Then: Early settlers found themselves here after coming ashore, and first homes and businesses were built here and in the area that is now Chinatown. For some years, this small concentration of development was San Francisco. The population explosion fueled by the gold rush drew larger businesses and financial institutions, all wanting to be headquartered in the busiest part of the city. High rise clusters that survived the 1906 earthquake were augmented during a late 20th-century skyscaper boom, forming the skyline. The distinctive Transamerica Pyramid was completed in 1972. One reason for the unusual shape was apparently to allow light to filter down from the sky to ground level. See related postcards.
How To Get There: The Financial District is a short walk from Union Square, zig-zagging a couple of blocks toward the northeast. You'll know you're there when you can't see the sun anymore. It's an even shorter walk from either the Montgomery or Embarcadero Muni/BART stations, due north or northwest, respectively.

Above the Financial District, from the Mandarin Hotel

Looking down at the Financial District

Montgomery Street at the Transamerica Pyramid

The base of the Transamerica Pyramid at Montgomery and Washington Streets

Entrance to the Transamerica Redwood Park, from Washington Street

Transamerica Pyramid against the sky

Redwood park at the base of the Transamerica Pyramid

Base of the Transamerica Pyramid at street level

Leidesdorff Street at Clay Street, on the south side of the Transamerica Pyramid

Commercial Street, between Leidesdorff and Sansome Streets

Tlaloc - Mexican on Commercial Street

Le Meridien Hotel on Battery Street near Sacramento

Kearny at Pine, near the base of the Bank of America building

Kearny Street

Restaurants on Kearny Street near Pine

Federal Reserve Bank of San Francisco

Sansome Street at California Street

Caffe Bianco on Sutter Street

San Francisco Soup Company is everywhere in the Financial District

Courtyard at Davis Street and California

Focaccia Cafe and Bakery on Sacramento Street

Tadich Grill on California Street near Front Street

The Bubble Lounge, on Montgomery Street near Columbus, for champagne and drinks

Tommy Toy's Chinese Cuisine on Montgomery

Perbacco - Italian cuisine on California Street near Front

Palio d'Asti on Sacramento near Montgomery

Aqua - seafood and American cuisine on California and Front Street