When Maximilian I of the powerful Hapsburg family decided not to bother with the Pope's approval to be Holy Roman Emperor in 1508 AD, he was saying that he thought the Hapsburgs were powerful enough to stand on their own. And so they were. Maximilian married everyone in his family to different rulers of Europe, so his kids inherited much more power than he had himself. In particular, Maximilian himself married the Mary the Rich, queen of Burgundy and the Netherlands, and Maximilian's son married Joanna, the daughter of Isabella and Ferdinand of Spain.
When Maximilian died in 1519, his grandson Charles V inherited Austria and the Netherlands. His mother Joanna was queen of Spain, but Charles kept her locked in a convent and ruled Spain, and all of Spain's colonies in North and South America too.
In 1526, when the Ottomans invaded Austria's neighbor Hungary, they succeeded in taking over the eastern half of the country. But three years later in 1529, Charles V was able to defeat the Ottomans - so he added the western half of Hungary to his empire. A year later, Charles' ships were sailing along the coast of California.
But at the same time, most of Germany was converting from Catholicism to Protestantism, and breaking away from the Catholic Holy Roman Empire. Charles V did his best to stop this with the Counter-Reformation and the Jesuits and the Inquisition in Spain, but he couldn't get Germany back. Then in 1540 Francis I of France convinced Suleiman to attack Austria-Hungary. Suleiman conquered more of Hungary, and to keep the rest Charles had to agree to pay money to the Ottomans every year as tribute.
Charles V retired in 1556, when he was 56 years old. He split his empire between his son, Philip, who got Spain, the Netherlands, and all the Spanish colonies, and his brother, Ferdinand, who got Austria-Hungary.
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