Complex sentence: When the Concertgebouw was built, acoustics were something of a "black art"; like in shipbuilding, designers drew upon what worked in the past without entirely understanding the underlying science (even today it is still not well understood).
Split into simpler sentences: When the Concertgebouw was built, acoustics were something of a "black art". As in shipbuilding, designers drew upon what worked in the past without entirely understanding the underlying science (and even today it is still not well understood).