the portsmouth guildhall is a massive building which is like the Sydney opera house but smaller and made of stone. If humans are gone, how long can it last with no maintenance?
Life After People
75 years after people Like the opera house, the Guildhill still stands because it's made of stone, not steel, but the windows have blown out.
150 years after people In Portsmouth, the Guildhall tower is coming unstable. Finally, it falls breaking off the remaining windows.
225 years after people In Portsmouth, the Guildhalls entrance is getting bigger finally the entrance falls.
300 years after people In Portsmouth, long after towers fell, the Guildhall finally falls to the ground of the new marshland.