It was long. It was loud. It was 1972. It was the Grateful Dead. — Perched royally, as if at the head of the table, flanking the west face of Museumplein opposite the Rijksmuseum, sits Het Concertgebouw (say: con-CERT-huh-bau). Completed in 1888, with its quintessentially pragmatic Dutch moniker, “Concert Hall” opened to a full house with support from 120 musicians and a 500-person choir who…