Kingsburg is the 25th level in Serious Sam 2.
After having to spend the night outside of Kingsburg's gates, The King's wife helps Serious Sam sneak into the city, where he learns that The King is going to celebrate his daughter's wedding. He decided to travel to The King's castle, the Castle of Rock. However, Mental starts teleporting his forces inside the city to stop Sam. Sam travels through the city and manages to reach the gate to a garden that leads to the Castle of Rock. However, the door is locked, so Sam decides to sneak it via the Royal Sewers.
1. Soon after starting the level, you will be presented with a fork in the road. Go left (the path with the blue Zagreb sign on it) and keep going until you get close to a sign that says “Zovi Samo Zovi”. When you're near it, look to your right, and you'll see several gold sparkles floating around. Walk into it, and you'll be teleported to a secret area that has a Football Players, a Treasure Chest and Large Armor. Note that all you need to do to register the secret is to walk into the teleporter.
2. Go back to the first area, but take the right path. As soon as you pass another blue Zagreb sign, look for a floating blue light thing above you. Blow it up with the XPML30 Rocket Launcher to make a Serious Damage fall to the ground. Pick up the Serious Damage to register the secret. If you need Rockets to blow the light up, look past the Zagreb sign and you'll find four rocket packs surrounding a tree. Note: if you can't find the blue Zagreb sign, look for the fourth floating blue light thing on the right path.
3. Continue following the right path, and you'll find an alley to your right. Go into it, then look across the wall. You'll see a Treasure Bag. Pick it up to register a secret.