Walking along the promenade, you'll come across El Cap de Barcelona, a sculpture by one of the greatest exemplars of American pop art, Roy Lichtenstein, who became famous for his huge cartoon vignettes. This surrealist statue created for the 1992 Olympics features the same cartoon-style features, but also represents a tribute to the great Gaudí and Barcelona architecture, and is made of both concrete and ceramics.
Now go along Passeig de Joan de Borbó. Before you get to the end of the road and reach the beach of Barcelona, turn off onto Carrer de Sant Carles. It's easy to notice that the neighborhood has a regular structure; in fact, it was designed by a military engineer. Plaça del Poeta Bosca is definitely worth seeing, as is the neighboring Plaça de la Font, with its market that takes you back to the atmosphere of the old fishing district.
I also suggest visiting the Church of Sant Miguel del Port, a Baroque-style church built in the 18th century. Its noble façade is horizontally divided into two levels by a tall attic, while inside you'll be amazed at how the white plaster coating seems to dilate the space.
Now pause the audio and go back to Passeig de Joan de Borbó all the way to the sea.
Barceloneta is the city's beach: it is a succession of beach and nautical clubs.
Continuing along Passeig Maritim you'll reach the Olympic Village, which is worth the walk: built for the 1992 Olympic Games, it is a sort of garden-town projected out towards the sea and immersed in a Mediterranean park. After the Olympics, the housing that had been built for the athletes and delegations was transformed into hotels, homes, equipped beaches, and sports facilities.
FUN FACT: if you see an igloo on the boardwalk, you're not hallucinating! It's a bar where the chairs, sculptures, and even glasses are made of ice and where the thermometer never goes over 8 degrees below zero. When you go inside, they loan you gloves and coats. Ideal for a hot summer day!