New York City has its share of abandoned history, but none quite like the Renwick Ruin on Roosevelt Island.

With its Gothic facade, the Smallpox Hospital, as it was once known, looks like some forsaken castle lost in time, better suited for the rolling terrain of rural Europe.

Indeed, the Renwick Ruin does represent another era, though not the medieval period its architecture would suggest. James Renwick, Jr. designed the hospital in the mid-19th century and sufferers of smallpox (a disease that killed some 300 million people in the 20th century alone) were quarantined there to safeguard New York City’s general population against the highly contagious disease.

When officials found a more suitable location to isolate infectious patients (at Riverside Hospital on North Brother Island, where Typhoid Mary once lived), the noble old castle became a nurse’s training facility and grew by a couple wings, but was deserted at the middle of the 20th century.

Health crises like the spread of the Ebola virus serve to remind us that, despite our best defenses, we are animals, vulnerable to microbes. But the Renwick Ruin is a reminder, too, of how far modern medicine has come, that a building once constructed because we feared a pernicious disease can now be appreciated for its obsolescence.

(Here is the Renwick Ruin on Google Maps.)

Views of the Renwick Ruin

L: FDR Four Freedoms Park; R: The Manhattan Skyline from Roosevelt Island