Requirements: the chests will be received by players level 15+

The main reward is the Lauriston Castle (4,200 coins, 1-3 energy, 2-3 Pearls every 24 hours, size 9x6, can be placed anywhere)
Each chest can be opened for 9 Summer keys.

There are 3 ways to get Keys:

Completing the quest:

Orienteering I (3 keys)
Collect 14 Ropes (Textile Factory, Upgraded Textile Factory)
Collect 14 Charms ( German house, Upgraded German House
Ask friends for 6 paint brushes

Orienteering II (3 keys)
Collect 4 bottles of Fish Oil (Drugstore)
Collect 7 Antique Vases (Jewelry Shop)
Ask friends for 5 Balls

Orienteering III (4 keys)
Collect 12 Pans (Hostel, Upgraded Hostel)
Collect 13 Bags of Chips (Harvest potatoes in Farm, Upgraded Farm)
Collect 11 Pirate Bandanas (Pub, Upgraded Pub)

2. Collect profits from the following buildings:

Central Station 1 key every (24 hours)
Museum of Paleontology 1 key every (8 hours)
San Diego Museum of Man - 2-3 keys every (23 hours)
Liverpool Royal Building - 2-3 keys every (24 hours)
Fisher Library 2-3 keys every (24 hours)

3. Use the sale offer!

Special offer:

Museum of Man in San Diego size is 7x7 can be placed everywhere

Every 24 hours:
4100 coins
1-4 energies
1-5 pearls
2-3 Summer Keys during the promotion