Chester Zoo has unveiled plans to build a £225m giant dome, transforming the site into Europe's largest conservation attraction.

Included in the plans is a 56 hectare indoor African-themed rainforest which will be home to gorillas, chimpanzees and other tropical animals. Unlike many other zoos in the UK, these animals will be allowed to roam freely around their habitats.

The dome alone is estimated to cost £90m and will form the first part of the zoo's transformation. It will be the first of its kind in Britain.

The £225m rejuvenation of Chester Zoo is called Natural Vision and will also include an interactive boat ride giving unique views of the animals, a conservation college and a new entrance which links the site to an adjacent marina.

Professor Gordon McGregor Reid, director general of Chester Zoo hopes that the transformation will effectively showcase the zoo's international conservation work which currently involves 50 countries across the globe.

"Natural Vision will offer a fun, family friendly, adventurous, yet educational window on the world of conservation," said the professor. "New and exciting animal species will be introduced. The project is unlike anything that has been in the UK and will offer a spectacular visitor experience and the highest standards of animal welfare."

Chester Zoo celebrated its 75th birthday in May. On average, approximately 1.3m people visit the attraction each year and in 2018, when the project is complete, that number is expected to rise to 2m.

The zoo currently occupies 50 hectares and will double in size when the new structure is complete.