Oakland’s waterfront, like many parts of the city these days, is changing rapidly.

New apartment buildings are popping up overnight, hip coffee shops seem to be on every corner, and wine boutiques are as common as office spaces.

Home to the Oakland Port and Jack London Square, the neighborhood has seen dense development, with residents and commercial interests moving into the historically industrial area. As a result, some of the city’s oldest relics and most humble histories are rubbing elbows with all that’s new to Oakland — out-of-towners, hipster shops and high-rise apartment buildings.

A free walking tour of Jack London Square and its surroundings captured this contrast Saturday morning, as tourists and residents gathered for a chance to explore the landmark and give historical context to a place too often known as “that city across from San Francisco.”

“Downtown Oakland is changing so rapidly, especially in the past 10 years,” said Annalee Allen, who coordinates the walking tours for the city. “It’s fun to go out and show people these things.”

Oakland’s waterfront is sleepy on Saturday mornings. Ships sit in their docks and the air is crisp and quiet, save for the long line of people waiting for the ferry to take them to San Francisco for the day. The Potomac, once a presidential yacht known as Franklin Roosevelt’s “floating White House,” sits docked nearby.

Just off the water, the area east of the port embodies Oakland’s industrial history. A railroad runs parallel to the waterfront. A red-brick building, now empty, has a fading sign: “Union Machine Works, machining since 1885.” Graffiti covers the remaining wall space. An old train station converted into offices sits on Third Street.

Old and new coexist on each block in the historic district, now home to many a fancy restaurant and quaint boutique. But way back when, Jack London Square was not a place to grab a nice meal. It was a bustling center of industry, separated from the city’s downtown and social life.

“It was not a place people were attracted to,” said tour guide Gary Knecht, who has lived in the area since 1982 and been leading tours since the ’90s. It was “a working port.”

The hodgepodge of architectural styles and building types — a mix of high and low, brick and stucco — tracks the area’s development. At the intersection of Third Street and Broadway, the city’s oldest building, built in 1859, sits catty-corner from a spanking new 18-story condominium.

For much of Oakland’s history, the waterfront was strictly industrial. But over the years, the area has become increasingly commercial. In 1950, a handful of lunch spots popped up in the area. In the 1960s, a motel was built on the waterfront. Now, a Bed, Bath and Beyond and Cost Plus World Market sit adjacent to abandoned industrial buildings. A huge parking structure sits across from a movie theater.

“There’s this conflict down here: Do you intensify development, or do you celebrate the (area’s) historic qualities?” Knecht said.

The tour is part of a greater effort by the city to expose residents and visitors alike to the rich history of Oakland. On the 90-minute walking tours, scheduled every Wednesday and Saturday through October, guides take people around different parts of town, reviewing history and discussing modern day changes to the city landscape.

The city has been offering free tours since the 1980s, when then-Councilman Richard Spees suggested the idea.

The program has since expanded to offer eight tours in various parts of the uptown and downtown neighborhoods. Most recently, it added an African American-themed tour that chronicles the stories of Lionel Wilson, Oakland’s first black mayor, and Robert Maynard, former owner of the Oakland Tribune, among others.

The tours capture both the city’s past and its ever-changing present. A walk of the Uptown neighborhood features the historic Sears Building, which will soon house Uber’s new headquarters. Several tours feature Latham Square, a historic plaza at the intersection of Broadway and Telegraph avenues that was restored and reopened just this summer.

Garrett Murphy has been going on the tours since the city started offering them. Born and raised in Oakland, Murphy said the tours help him understand the city’s changing landscape.

“It helps me keep up with the development,” he said.

Berkeley resident Mary Marshall has been on three of the Oakland tours, which she said help her get to know the city in a new way.

“It gives me a history of what happened in Oakland,” Marshall said. “It’s a great place. It’s underestimated.”

Libby Rainey is a San Francisco Chronicle staff writer. Email: lrainey@sfchronicle.com Twitter: @rainey_l