A page with a (sub)domain name which is a palindrome (i.e. it is the same when read backwards)
A page with the same domain, expanded to a palindromic URL
A page with a (sub)domain name which is an ambigram (i.e. it is the same when read upside down)
A page with the same domain, expanded to a ambigrammatic URL
To the best of my knowledge, this is one of only two URL ambigrams in the internet.