Complex sentence: In 1821, the infirmary was reaching capacity, treating nearly 10000 patients a year, so a new site was found, at 28 Villiers Street, near Charing Cross in the heart of the metropolis.
Split into simpler sentences: In 1821, the institution began to reach capacity, treating nearly 10000 patients a year. A new site was found at 28 Villiers Street, near Charing Cross in the heart of the metropolis.