At sunset, it’s a gas in L.A.

LOS ANGELES is often derided as a city with little sense of history, when in fact history is everywhere you turn -- in the stately mansions of Hancock Park, the grand old facades of downtown office buildings, the Craftsman and Spanish-style bungalows sprinkled throughout the older suburbs.

When the sun sets each evening on the architecture, the history lesson does not end. Many of the neon signs atop the city’s hotels, theaters and restaurants are decades old and offer a peek back at the city’s diverse commercial heritage.

The Museum of Neon Art in downtown L.A. sponsors a weekly bus tour of these neon landmarks. On Saturday nights from June through October, passengers ride around town in a red double-decker bus to view neon signs old and new, artful and tacky, and to learn a few random facts about neighborhoods from downtown to Silver Lake to Mid-Wilshire.

Whether it’s the cheerful baker at Canter’s Deli carrying a plate piled high with bread or the famous blue-and-red beacon marking the Wiltern LG theater, Los Angeles has one of the best-preserved collections of vintage neon signs in the country.

“We look at cool signs and enlighten Angelenos about their neon heritage,” Kim Koga, the museum’s director, said of the bus tour.

As the neon cruise got underway one recent Saturday, the sky was still bright. Guide Max Pierce entertained the riders, who all sat on the upper deck of the bus, with factoids about the downtown business district they were passing through. At nearly every corner, Pierce pointed to an old commercial building that was being converted to residential lofts.

Cole’s and Philippe, which both claim credit for inventing the French dip, have vintage neon signs, Pierce noted as the bus passed by the restaurants. To the south, on Spring Street, the red and blue neon strips on the Caltrans building are among the city’s newest neon additions. Even the drabness of skid row is enlivened by pale blue neon on a single-room occupancy complex.

In Chinatown, the bus stopped briefly at Central Plaza, where the riders got off for a quick look at the art galleries and souvenir shops. Night was falling, and the green neon outlining the pagoda-style entrance to the plaza was beginning to stand out festively.

“Although people might say that L.A. isn’t interested in its past, if you look beneath the surface, there’s history there. It’s not necessarily cared for, but it’s there,” said Pierce, a historian and freelance writer.

SCIENTISTS as far back as the 17th century observed that some gases glowed in the presence of electricity, and by the early 1900s there were various glowing-gas lamps, including carbon dioxide-filled commercial signs. But it was not until French inventor George Claude applied an electric charge to a tube of neon gas that neon lighting was born. Claude introduced his neon lamp to the public in Paris in 1910.

In 1923, Los Angeles became home to America’s first neon signs when a Packard car dealership downtown purchased a pair from Claude.

Over the next two decades, neon signs sprouted in Los Angeles’ theater district, on grand apartment buildings such as the Gaylord and on cheap motels lining Route 66 (now Sunset Boulevard), bringing the night skyline to life with a splash of futuristic colors.

Plastics technology leaped forward during World War II, and plastic signs lighted with fluorescent tubing became cheaper than neon. The number of neon craftsmen in the United States declined from about 5,000 at the end of World War II to fewer than 500 in the early 1970s.

Neon has since experienced something of a resurgence, and newly minted neon graces Amoeba Music on Sunset, as well as the ubiquitous red-and-blue “Open” signs in restaurant windows.

Too cumbersome to dismantle, the old neon signs were often left in place even after the businesses they advertised had long disappeared. The neon museum, partnering with other local organizations, has helped to restore some of those signs and keep them lighted.

Pierce pointed out one of those restored signs to his passengers: the Bendix Aviation sign, with a 25-foot-tall B, which was used to guide aircraft in the 1930s and ‘40s.

In the old theater district too, some neon signs shine as brightly as ever, even though the glory days of the grand movie halls are long over. The Mayan’s distinctive sign now steers customers to a nightclub. The Orpheum’s shifting yellow-and-red neon and the Los Angeles Theatre’s gold sign still light up Broadway, even though both venues are now used only for special events.

After the theater district, the bus lumbered down Sunset along the old Route 66, through Hollywood and back east on Wilshire, with a pit stop at Canter’s. There was the 1920s vintage neon on the seedy-looking Olive Motel; the green neon on the elegant Vista Theater; the neon signs advertising the House of Freaks body piercing parlor on Melrose and the Bryson and Asbury apartments near Lafayette Park.

Following the neon trail, the bus had gone by a good number of the city’s best-known landmarks east of Fairfax. Some of the riders said they found the tour more interesting for the local history than for the neon.

“I’ve lived here for 22 years, and I know very little about the history,” said Sandy Ivanhoe, 56, a writer and retired nurse from Pacific Palisades who was on the neon tour with her husband and another couple. “The Bunker Hill part was really interesting -- I wasn’t even sure where it was before.”

The neon tours have run occasionally since the early 1980s, but the museum did not make them a weekly event until about three years ago. Pierce and J. Eric Lynxwiler, another local historian, switch off as guides.

This year, the museum started a Poet’s Beat neon cruise that will carry over into the winter months, when it is too cold for the open-air double-decker. The new tour, if still a learning experience, is merrier: It features music related to neon and local history -- and stops at bars.

*

Neon Cruise

Where: Departs from Museum of Neon Art, 501 W. Olympic Blvd., Suite 101, downtown L.A.

When: Cruises are Saturday nights through the end of October; the next Poet’s Beat cruise is Aug. 19

Price: $45; $35, museum members. Poet’s Beat cruise, $25; $20, members. Reservations required.

Info: (213) 489-9918, www.neonmona.org