How can I get the baseurl of site?

I want to write a little helper method which returns the base URL of the site. This is what I came up with:

public static string GetSiteUrl()
{
    string url = string.Empty;
    HttpRequest request = HttpContext.Current.Request;

    if (request.IsSecureConnection)
        url = "https://";
    else
        url = "http://";

    url += request["HTTP_HOST"] + "/";

    return url;
}

Is there any mistake in this, that you can think of? Can anyone improve upon this?

Try this:

string baseUrl = Request.Url.Scheme + "://" + Request.Url.Authority + 
    Request.ApplicationPath.TrimEnd('/') + "/";

string baseUrl = Request.Url.GetLeftPart(UriPartial.Authority)

That's it ;)

The popular GetLeftPart solution is not supported in the PCL version of Uri, unfortunately. GetComponents is, however, so if you need portability, this should do the trick:

uri.GetComponents(
    UriComponents.SchemeAndServer | UriComponents.UserInfo, UriFormat.Unescaped);

I believe that the answers above doesn't consider when the site is not in the root of the website.

This is a for WebApi controller:

string baseUrl = (Url.Request.RequestUri.GetComponents(
                    UriComponents.SchemeAndServer, UriFormat.Unescaped).TrimEnd('/') 
                 + HttpContext.Current.Request.ApplicationPath).TrimEnd('/') ;

To me, @warlock's looks like the best answer here so far, but I've always used this in the past;

string baseUrl = Request.Url.GetComponents(
    UriComponents.SchemeAndServer, UriFormat.UriEscaped)   

Or in a WebAPI controller;

string baseUrl = Url.Request.RequestUri.GetComponents(
    UriComponents.SchemeAndServer, UriFormat.Unescaped)

which is handy so you can choose what escaping format you want. I'm not clear why there are two such different implementations, and as far as I can tell, this method and @warlock's return the exact same result in this case, but it looks like GetLeftPart() would also work for non server Uri's like mailto tags for instance.