London's promotional organization said Thursday that the capital's giant Ferris wheel, the London Eye, will be lit in red, white, and blue, after the birth is announced.
An exhibition featuring clothes worn by former royal babies has already opened at the Museum of London.
The expected arrival of Kate and William's first child has sent reporters into a tizzy.
Dozens of reporters have already staked out the central London hospital where the Duchess of Cambridge is expected to give birth. The Palace has said only that Kate is due to deliver the baby in "mid-July."