The Main Building is the zoo's entrance point set at the front of every zoo. It is fixed in place, and cannot be moved, removed, or sold, although it's appearance can change. The main building features a menu when clicked, where players can choose to collect revenue, create an avatar, visit the safari, wheel of fortune, or secret zoo, or change the main building's design.
The Main Building gathers admissions revenue from visitors in the form of pet pennies. Profits are available for collection when a rotating coin appears above the building and the progress meter is full green. Unlike buildings within the zoo, the Main Building's pet penny capacity is greater than one cycle of earnings. If profits are left uncollected, they will accumulate (to a point). The pet penny capacity of the Main Building increases as a player levels up.
In May of 2011, designs were introduced for the Main Building. Initially, the Main Building's default design is all that's available. Every ten levels an additional design is unlocked, up to level 40. The decision to use one design over another is purely aesthetic and the various designs offer no in-game benefit. The 7games extension makes a sixth design available.
The Main Building provides shortcuts to the Safari, the Wheel of Fortune, and the Secret Zoo (this option is dimmed if the Secret Zoo is not yet available). There are other ways of accessing these parts of ZooMumba, but gathering shortcut links together at the Main Building can be helpful.
Additionally, players can create or edit their avatars via the main building menu.