Get site url (mulisite directories?) php code?

<?php get_site_url(); ?> = domain.com/

domain.com/site1/about
domain.com/site2/about
domain.com/site3/about

What’s the direct php code to link to these separate sites and accomplish this?

<?php echo network_site_url(); ?>

doesnt work either, I’m guessing it’s the same code as above, just for multisite purposes?

Try this : https://snipplr.com/view/44349/

Not sure what that is? or how that relates to the hyperlink/url?

got it:

<?php echo get_bloginfo('wpurl'); ?>