Allen Ruppersberg is known for creating artworks that masquerade as ordinary objects, such as a diner, a hotel, a novel—and now, a wall.

The artist spent a Thursday in September at the Getty Research Institute creating L.A. in the 70s, a site-specific installation for the title wall of Greetings from L.A.: Artists and Publics, 1950–1980. The show, which opened October 1, borrows its title from Ruppersberg’s 1972 book, a Tinseltown exposé that boasts hilarious back-cover copy—and rises above the competition by being almost entirely blank inside.

The wall centers around a vinyl blow-up of Al’s handwritten cover for Greetings, in bright green and yellow inspired by his print L.A. in the 70s. (It was slightly weird, Al admitted, to see his own youthful handwriting—more legible than today’s—at some 25 times actual size.) Enhancing the time-machine vibe are repros of city maps he scored at a flea market in the early seventies. Best “how times have changed” moment: a point on the map marking L.A.’s only Art Museum at Wilshire and Fairfax.

The handwriting and maps form the backdrop for a massive collage of 40 asphalt-jungle photos of L.A., placed by the artist one by one. Four decades have passed, but this is still our city: cars, taco stands, signs for beer and parking.

An artwork in itself, the wall also cannily preps you for the cacophony of L.A. moments to come right around the corner in the exhibition, which features hundreds of treasures from the Getty Research Institute’s archives of L.A. art—including other pieces by Ruppersberg, such as Al’s Grand Hotel (1971), 24 Pieces (1970), and, of course, Greetings from L.A.

When the show closes on February 5, L.A. in the 70s comes down. Luckily the collage, in true L.A. spirit, is hip with making way for the next thing.