Leaning Tower Optical Illusions are really just perspective illusions.  By lining up objects and different depths you can create an optical illusion that they are the same or similar size, in this case leaning towers. The first picture is the famous Leaning tower of Pisa.
The second picture of a clock tower was taken at Puzzling World in New Zealand.

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Leaning Tower of Pisa Optical Illusion

Puzzling World Leaning Clock Tower Optical Illusion