McDonaldland was a fantasy world used in the marketing

Marketing

Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 for McDonald's

McDonald's

McDonald's Corporation is the world's largest chain of hamburger fast food restaurants, serving around 64 million customers daily in 119 countries. Headquartered in the United States, the company began in 1940 as a barbecue restaurant operated by the eponymous Richard and Maurice McDonald; in 1948...

 restaurants. It was based on the "total concept and feel" of Sid and Marty Krofft's

Sid and Marty Krofft

Sid Krofft and Marty Krofft , are a sibling team of television producers who were influential in children's television and variety show programs in the USA, particularly throughout the 1970s and early 1980s....

 H.R. Pufnstuf

H.R. Pufnstuf

H.R. Pufnstuf was a children's television series produced by Sid and Marty Krofft in the United States. It was the first Krofft live-action, life-size puppet program. The seventeen episodes were originally broadcast September 6, 1969 to September 4, 1971...

television program. McDonaldland was inhabited by Ronald McDonald

Ronald McDonald

Ronald McDonald is a clown character used as the primary mascot of the McDonald's fast-food restaurant chain. In television commercials, the clown inhabits a fantasy world called McDonaldland, and has adventures with his friends Mayor McCheese, the Hamburglar, Grimace, Birdie the Early Bird, and...

 and other characters. In addition to being used in advertising

Advertising

Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...

, the characters were used as the basis for equipment in the playground

Playground

A playground or play area is a place with a specific design for children be able to play there. It may be indoors but is typically outdoors...

s attached to some McDonald's. McDonaldland and the supporting characters have been abandoned in their marketing, but Ronald McDonald is still seen in commercials and in Happy Meal toys.
The first phase of the McDonaldland concept began in January 1971, about the same time McDonald's was replacing its drive-ins with mansard roof

Mansard roof

A mansard or mansard roof is a four-sided gambrel-style hip roof characterized by two slopes on each of its sides with the lower slope at a steeper angle than the upper that is punctured by dormer windows. The roof creates an additional floor of habitable space, such as a garret...

ed restaurants.