reverse-proxy with nginx: using an existing https site as backend

I have one site somewhere that’s accessible on the internet as “”.

I also have one another site accessible on the internet as “”.

I have full control over both sites and they both have valid Certificates.

Now I want to have the first site to be accessible as a location on the second; this means that “” should display the contents of “”.

I tried a plain:

location /site {
    proxy_pass              "";
    rewrite                 /site/(.*) /$1     break;
    proxy_redirect          off;
    proxy_set_header        Host               $host;

but this does not work well because browser (accessing “”) is presented server certificates from backend (“”) which are invalid for the request.

How can I force nginx front-end to send out its own certificates and verify backend identity on its own?