Simplify the following text for a Grade 15 native English-speaking person.
Original: Tourism is a big earner for the province , with most of the tourism centred around the old city of Trinidad , a World Heritage listed city which has dozens of colonial buildings ( and almost no 20th century architecture ) dating back to the Spanish conquest in the 1500s , and , as with most of Cuba , sugarcane and cattle are important commodities .
Simplified: Tourism is a big earner for the province , with most of the tourism centred around the old city of Trinidad , a World Heritage listed city which has dozens of colonial buildings ( and almost no 20th century architecture ) dating back to the Spanish conquest in the 16th century .