I'll open this thread with a famous piece...
The Dictator
This 13-inch Model 1861 seacoast mortar was perhaps the most famous mortar used during the war. The Dictator was mounted on a specially reinforced railroad car designed to accommodate its impressive 17,000 pounds.
The gun was served by Company G of the 1st Connecticut Heavy Artillery for three months during the siege of Petersburg, Virginia in 1864.
The Dictator was capable of lobbing a 200-pound explosive shell approximately 2 ½ miles into the city from its firing position on a curved section of the Petersburg & City Point Railroad track.