It is impossible to talk about the Civil War in New York without remembering that it once had been the second-largest slaveholding city in the United States. While gradual emancipation began in 1801, New York did not fully free its enslaved citizens until 1827, making it the second-to-last northern state to do so (only New Jersey came later). Many early enslaved Africans found their final resting place in the swampy area north of City Hall. In 1991, construction workers digging the foundation of a new federal office building unearthed the first of 424 graves of black New Yorkers—both free and enslaved—one of the largest such archaeological discoveries ever.

Once the war began, City Hall Park—the city's de facto town square—played a crucial role. It was here that enlistment offices were set up to recruit Union volunteers. When Mary Todd Lincoln visited the city soon after her husband’s inauguration, she reviewed troops at the "park barracks," very likely set up here. After Lincoln's assassination, his body lay in state in the rotunda of City Hall, April 24-25, 1865. It was here that the only known photo of him in his coffin was snapped by an enterprising photographer. [Photo of City Hall & City Hall Park in 1911 via Wikimedia Commons.]

A century and a half later, photography remains crucial to our experience of the war, and no photographer from that era was more celebrated than Mathew Brady. Brady had a number of studios in the city, but the only one that still stands is at 359 Broadway in Tribeca. Brady occupied the third floor of this building from 1854 to 1860, before relocating to Broadway and Tenth Street. While it has sometimes been reported that Brady's famous 1860 portrait of Lincoln was taken here or at the Tenth Street location, he almost certainly took it at his Bleecker Street studio. Lincoln credited the Brady photo and his Cooper Union speech with winning him the presidency. The building, although a landmark, isn't much to look at; the ground floor houses PS Fabrics and there are commercial tenants on Brady's floor.

Arguably, New York’s oldest continuously operating bar—opened in 1854—McSorley's was also the spot where Peter Cooper supposedly hosted Lincoln after his speech at the nearby Cooper Union. This seems unlikely in that Lincoln was both a teetotaler and had a previous engagement. Nevermind. McSorley's was certainly a popular hangout during the Civil War and still features a WANTED poster for John Wilkes Booth, printed during the twelve days the assassin was on the lam. [Photo via Wikimedia Commons.]

Following the passage of the Fugitive Slave Act, it became imperative to get runaway slaves across the border to Canada lest they be caught and returned to their masters. Many New Yorkers housed slaves as part of the Underground Railroad—many more than for whom there is documentation. One location was the home of David Ruggles, an African American freedman who founded the New York Committee of Vigilance and who devoted his short life to manumission. Though Ruggles died in 1849, his home still stands as a monument to him and the slaves sheltered there. Ruggles's home now features the cafe La Colombe Torrefaction; a plaque just west of the entrance to No. 36 details its role in the Underground Railroad.[Photo via Property Shark.]

Soon after Lincoln's first inauguration in 1861, Mary Todd Lincoln came to the city on the first of many shopping trips. One goal while in the city was to order a new set of White House China (Lincoln's predecessor, James Buchanan, had been a terrible housekeeper), so she made a beeline for E.V. Haughwout's china emporium. Already famous as the first building to have a working passenger elevator, Haughwout's team designed and fabricated new dinnerware for the first lady, which is sometimes still on display at the White House. If you want to get a small glimpse of what Mary Lincoln experienced, clothier Bebe occupies the retail space. Corcoran has offices above. [Photo via Wikimedia Commons.]

When the saboteurs set fire to a room at the La Farge Hotel, smoke began to leak into the Winter Garden theater next door, interrupting the performance of Julius Caesar taking place. The show that night was a special benefit to raise money for a statue of William Shakespeare to commemorate the playwright's 300th birthday. What made the play extraordinary was that it was the first time the three Booth brothers had acted together: Edwin Booth was America's leading tragedian (his home is now the Players Club on Gramercy Park). Brother Junius is now mostly forgotten, but the third Booth, John Wilkes, would achieve infamy five months later at Ford's Theater with the murder of the president.

The minister of the Plymouth Church, Henry Ward Beecher, was the most famous abolitionist in New York. From the pulpit of the church he would host mock slave auctions, showing parishioners how fellow humans were sold like chattel. The basement of the church was the "Grand Central" of the Underground Railroad and Lincoln's appearance here on February 26, 1860, meant he was clearly throwing his weight behind the the anti-slavery movement. In the courtyard next to the church, a statue of Beecher by Gutzon Borglum shows him exhorting his followers. Inset in the wall is a magnificent bas relief of Lincoln, beaten down by the horrors of war. The Plymouth Church holds regular Sunday services and is occasionally open for tours. [Photo via Wikimedia Commons.]

One of the most important communities of free blacks in New York before the Civil War, the town of Weeksville was founded in 1840s. Three houses remain, one of which is set up to show what life was like for a free African American family during the Civil War. During the draft riots of 1863, as blacks fled lynchings in Manhattan, some ended up taking refuge in Weeksville. Though the center boasts a new, state-of-the-art visitors center, it is currently not open for casual visitation.

New York's many military installations saw no action during the Civil War, but they did see plenty of prisoners. Castle Williams on Governors Island, which had been built to protect the harbor during the War of 1812, was first used as a barracks for soldiers being shipped off to the front. Later, it was converted into a prison for Confederate POWs. In summer months, when Governors Island is open to the public, the National Park Service runs tours of Castle Williams and other historic sites on the island.