aldoc: It is not the worlds first 180mm F2.8 Macro, but the first to go to 1:1 without additional tube. I have before me a review of 1996 Chasseur d'Image magazine about a "Sigma AF 180mm f/2.8 Apo Macro" with the then famous "Zen" finish ( ;-) ). Conventional AF and MF versions were made alongside at this time, no OS of course, 13 lenses in 11 groups including some ED elements. Minimal focus 0.64m, (0.5x). 85mmx180mm, weight 1580 g, Filter 82mm. It was made in a big variety of mounts: FD, EF, MD, MAF, NI-AF, NI-AIS, SA and K -- long, long time ago... BTW Price 8490 FF, maybe around $ 2000.- in todays world.
I have one of those -- a 90's Sigma 180/2.8 APO Macro in Nikon mount.
Great optics, although the finish rubs off (no surprise there) and the tripod mount is poorly designed and really doesn't lock properly. This tends toward a loosey-goosey attachment rather than a secure one, which you don't want with such a long macro.