The exactly solved model invented by Sutherland and the speaker in 1981
has very recently lead to a class of two dimensional systems
SrCu_2(BO3)2,
Tm B4.... that are
currently exciting. In this talk I will summarize the recent
experimental systems that have been found, and also some key ideas from
quantum antiferromagnetism and Mott Hubbard physics that are tested.
The underlying lattice has apparently an ancient history dating back to
the concerns of Archimedes, and according to many workers, the lattice
and the model have an intriguing future as well, providing a testing
ground for current ideas on unusual quantum phenomena.