First Things First:

Click on each magnifying glass to learn more about the source.

Map of Alexandria, Virginia marking Civil War hospital sites, barracks, and cemeteries with red icons across the street grid near the Potomac River.
Mansion House was a hotel that became a hospital during the war.
Camp Convalescent was a hospital complex called "Camp Misery" by the soldiers.
L'Ouverture Hospital was a former pen for holding slaves awaiting sale that became a hospital for African American soldiers.
Think about it:

Look at the sites that are highlighted (marked). What function does the largest number of buildings serve? Why might that be?