The Antoninos

Melusina is said to have been the wife of the founder of Luxembourg, Count Siegfried.

When they married, she had one particular request, namely that Siegfried must leave her alone for one full day and night every month. Melusina was such a beautiful girl, that Siegfried could not refuse her this one small wish.

All went well for years: on the first Wednesday of the month, Melusina would retire into her chambers in the "Casemates", a network of caverns underneath the city, not to be seen again until early light on Thursday.

But inevitably Siegfried's curiosity got the better of him and he peeped through the keyhole to find Melusina lying in the bathtub, with a fishtail hanging over the rim.

Since mermaids have a very keen sixth sense, she recognised her husband through the door and jumped out of the window into the river Alzette below, never to be seen again...

Although every now and then people say they saw a beautiful girl's head pop out of the river and a fishtail rippling its calm waters...

Edited from http://www.luxembourg.co.uk/legends.html