def largest_histogram(heights):
    stack = []
    best = 0
    for i in range(len(heights) + 1):
        current = heights[i] if i < len(heights) else 0
        while stack and heights[stack[-1]] > current:
            height = heights[stack.pop()]
            left = stack[-1] if stack else -1
            best = max(best, height * (i - left - 1))
        if i < len(heights):
            stack.append(i)
    return best