You may well rub your eyes but, yes, it's true: the location is the Pontifical Institute for Sacred Music in Rome!
Alessandrini's vision of Vivaldi's music is tactile, even sensual, orientated towards a physical experience of time itself (just watch how he conducts!). In my view this recording represents a milestone in the deepening of our understanding of this music. I look forward for comparison to the release next month of Fabio Biondi's recording of Ercole su'l Termodonte, with the wonderful Vivica Genaux (of whom more anon).
Around 45 operas by Vivaldi have survived (though not all complete). Of these at a guess around 2 dozen have been committed to disc. Vivaldi himself boasted of having written 94! - and lost works are being rediscovered all the time, including, recently, a flute concerto in Scotland! Who knows what joys await us?