One of the greatest events in my city.

Today I am going to talk about "Arde Lucus", a celebration that takes place in mi city in June every year. It lasts three days, during which nearly everybody dresses up in a Roman costume.
There are a lot of activities to do and assist to during these three days, like assisting to a lot of representations about the way of living of the Romans, if you have kids you can bring them to a lot of activities and you can even marry somebody in the Celtic way.
I always have a lot of fun in this celebration because I really like to see everybody dressed like a Roman, the weather is usually good, there are a lot of amusing things to do and everybody is in a great mood.
I know that Arde Lucus isn't like Oktoberfest or any really big well-known event, but if you are going to visit a nearby city or my city someday I would definitely recommend you to assist to it, because is it incredibly fun!.

The main correction I would recommend:  In English, "assist" means to help someone with an activity that the other person is doing.  A better word is "attend":  "There are a lot of activities to do and to attend during these days."    "Like attending a lot of representations about the way of living..."    In English we say "attend" and do not need the word "to" to follow it in most cases.  Again in your last sentence, "I would definitely recommend you attend, because it is incredibly fun!"