1) The word "guitar" contains three vowels: U, A, and I.

2) The Industrial Revolution led to significant urbanization, as people migrated from rural areas to cities in search of employment in factories.

3) The first commercially successful video game was "Pong," released in 1972 by Atari.

4) The Sydney Opera House, situated in Sydney, Australia, is an iconic architectural masterpiece and a UNESCO World Heritage site. Its unique design, resembling sailboats or shells, has made it one of the most recognized and photographed landmarks in the world.