1.In 1707, the Acts of Union brought together England and Wales with Scotland making Great, (or Greater), Britain.
Great Britain isn't a country. It's the island that England, Scotland and Wales share. You're probably thinking of the 'United Kingdom' which isn't a country either.
2. The Tower of London is a historical castle in the capital city of England. It is located in central London on the river Thames. The tower has a rich history and has been besieged several times. It has also been used for a variety of different purposes over the years including; royal residence, treasury, Royal Mint, prison and home of the Crown Jewels. However, the White Tower, where the Tower of London get its name, was built by William the Conqueror. Construction is thought to have started in 1078 and many historians believe that it wasn’t finished until after William had died.
3. yes, they did.