### Use case
# example.com has a non-WordPress installation at its root
# example.com/blogs is a WordPress multisite sub-directory installation
# example.com/blogs/blog1 is a site in WP multisite
# example.com/blogs/blog2 is another site in WP multisite
# The site would be accessed primarily as example.com (instead of www.example.com)
# Please replace blogs with the actual name of the sub-directory inwhich WP is (would be) installed

### Remember that IfIsEvil, if used inappropriately.
# Ref: http://wiki.nginx.org/IfIsEvil

# Redirect www.example.com/anything to example.com/anything
server {
    listen 80;
    server_name www.example.com;
    return 301 $scheme://example.com$request_uri;
}

# Process requests to example.com
server {
    listen 80;
    server_name example.com;
    index index.php;

    # Change this to the actual location of non-WordPress files
    root /home/username/sites/example.com/public;

    # Logs
    access_log /var/log/nginx/example.com-access.log combined buffer=64k flush=5m if=$loggable;
    error_log /var/log/nginx/example.com-error.log;

    ### modified version of globals/mu-files.conf;
    # For uploads
    if ( $uri ~ "files" ) {
        rewrite ^/blogs/(?:.*/)?files/(.+) /blogs/wp-includes/ms-files.php?file=$1;
    }

    ### modified version of globals/mu-dir.conf;
    # For sub-directory redirects
    # Only one would apply
    # If two needed to be applied, it'd throw a 404
    if (!-e $request_filename) {
        rewrite  ^/blogs/[_0-9a-zA-Z-]+(/wp-(content|admin|includes).*) /blogs$1 break;
        rewrite  ^/blogs/[_0-9a-zA-Z-]+(/.*\.php)$ /blogs$1 break;
    }

    # Process PHP requests
    location ~ \.php$ {
        try_files                   $uri               =404;
        fastcgi_split_path_info     ^(.+\.php)(/.+)$;

        include "fastcgi.conf";
        fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
        fastcgi_index               index.php;
        fastcgi_pass                fpm;
    }

    # To process WordPress site/s
    location /blogs {
        try_files $uri $uri/ /blogs/index.php$is_args$args;
    }

    # Let's include usual location directives, including 'location / { try files ; }' directive
    # To process the non-WordPress PHP site
    include globals/assets.conf;
    include globals/restrictions.conf;

    # The rewrite magic
    location / {
        try_files $uri $uri/ /index.php$is_args$args;
    }

}