Complex sentence: He found out that there was an abandoned printing house in the Bishop's Palace in the city, and asked his long time friend Aleksandar Mikulić, who had by that time become the bishop, to let him put it to use.
Split into simpler sentences: He found out that there was an abandoned printing house in the Bishop's Palace in the city. He asked his long time friend Aleksandar Mikulić, who had by that time become the bishop, to let him put it to use.