You don’t let it run...on ;)
Haha nah, depends on the sentence. There’s many ways to shorten a sentence. It just depends on what the sentence is about
Could you post the lines of two and four so I could see what they look like?
This building was built over 100 years ago and features a design not seen on many other buildings of the era as well as a large collection of furniture and art.
No, this is a complex sentence because it contains an independent and a dependent clause.