Building a WordPress site on an Existing Domain

All,
I need to build a wordpress site on a domain that already has a site using html.

I don’t want the existing site to be down, but I want to build the wordpress site in the background and then once I am done, I want to make the wordpress site the active site.

Is there an easy way to do this, without going through a lot of configuration changes?

Please help if you can.

Thanks in advance!