The travel through time. Going from the Pyramids to the Castles to the Skyscrapers, and further to the future. Every object in this piece symbolizes time, from a long time ago to where we are today. The man on the boat goes from the past to the current time and will continue to travel towards the future. Which will give new opportunities and also Dramas.
That’s also why I put a Destroyed castle in there, opinions and morals from the past change (luckily). This will show growth and prosperity in the skyscrapers.
The sun going down means the end of the day which will make the day the past. The man on the boat will experience the Sunrise which will be the future. The previous day will be the past for him, and maybe one day his boat will get an upgrade.