The first act in the history of the Seminar, from the moment we decided that what we had been doing for several years now was actually a some serious solid Seminar, was a lecture by J. Neukirch about Poincaré's duality in number theory, and tooke place in October 9, 1986, from 15h 30min to 16h 45min, at the Facultat de Matemàtiques of the Universitat de Barcelona.
From that first act as a formal seminar, and with the drive, direction and organization of Pilar Bayer yet from its pre-history, the Seminar has grown larger until to reach a benchmark for annual meetings of Number Theory researchers; so large that even a collegiate management has become convenient.
The story of the early years of the STNB was essentially covered in the article Arithmetical Problems in Number Fields, Abelian Varieties and Modular Forms, which we refer to.
A very personal view of its pre-history and a part of its later history, until 2016, can be found in the Hommage to Pilar Bayer.
And the rest, it still has to be written.