Forts are almost always built to defend a town. However we cannot give you an answer here as you neglect to say WHICH 'old fort' you want to know about. -Please give as much information as possible when asking questions. In questions like this a place and a date are very helpful.
It was built in 1805.
Purana Quilla (old fort)
The Red for is a 400 year old fort built in the city of Delhi in India. It was built by the Mughal emperor named Shah Jahan, who used to rule the inner city known as Old Delhi.
fort william was built in 1781
it was built on the ft.wood or the liberty island to make a good educated guess
King Yaduraya first built a palace inside the Old Fort in Mysore in the 14th century.
the fort in Dubai museum is situated was built in
What year was Fort St.Louis built?
Allahabad Fort was built by Emperor Akbar
Allahabad Fort was built by Emperor Akbar
Fort St. Louis was built in the summer of 1685.
Fort Santiago is in Intramuros, a walled section of the city of Manila, in the Philippines. It was built by the Spanish conquistadors beginning in 1571, on the site of an old palisade fort.