The First Man in Rome (Masters of Rome #1) by Colleen McCullough (1990, First edition)

From the bestselling author of The Thorn Birds comes a masterpiece of historical fiction that is fascinating, moving, and gloriously heroic. The reader is swept into the whirlpool of pageantry, passion, splendor, chaos and earth-shattering upheaval that was ancient Rome. Here is the story of Marius, wealthy but lowborn, and Sulla, aristocratic but penniless and debauched -- extraordinary men of vision whose ruthless ambition will lay the foundations of the most awesome and enduring empire known to humankind.

A towering saga of great events and mortal frailties, it is peopled with a vast, and vivid cast of unforgettable men and women -- soldiers and senators, mistresses and wives, kings and commoners -- combined in a richly embroidered human tapestry to bring a remarkable era to bold and breathtaking life.