There are yet no plans for building space colonies by any large-scale organization, either government or private. However, many proposals, speculations, and designs for space settlements have been made through the years, and a considerable number of space colonization advocates and groups are active.

Why space colonization is impossible?

Perhaps humans are not built for space. We evolved on Earth, so many parts of our biology are not well suited to life beyond Earth. ... Ultimately, our biology is not designed for extraterrestrial environments, making colonization impractical or maybe even impossible.

What planets can we colonize?

Bodies in the inner Solar System have been considered for terraforming and space colonization. The main candidates for colonization in the inner Solar System are Mars and Venus. Other possible candidates for colonization include the Moon and even Mercury.