Heard of Upper deck, But Lower deck ?
Yes, that's what I found in a Lufthansa Airbus A340-600 plane.
I have seen Boeing 747-400 megatops with its upper deck passenger cabin. But, experienced the lower deck for the first time in a Lufthansa plane. This Airbus A340-600 had the Toilets / Lavatories in the lower deck. One had to walk down a flight of stairs to get to the facilities. The good thing with this setup was that there were more facilities than usual, but it did cause mild traffic jam due to the concentration of facilities at one place.
Lower deck facilities in the middle of the plane
Did some looking around on Airbus site and found that, there are only 59 of A340-600 are with 5 airlines globally. Lufthansa has 10 of these planes and none with any Indian Airlines.