Incredible vintage 70s black polyester Victor Costa evening dress.
The bodice and sleeves are made of sheer netting fabric, with lining around the breast part and lace on the upper shoulders.
Wide waist and pleated at the skirt. 
Keyhole opening in the back. One button at the back of the neck, and zips in the back.
Impeccable condition! No flaws to note.

The last photo is of the inside bust so you can see the outline of the part that covers the breast.

length: 58
bust: 34-36
waist: 26
hips: free
sleeves: 24
shoulders: 15.5