Filipino churches built during Spain’s colonial period used millions of egg whites in the mortar to make it more durable. This is also why Filipino desserts often use lots of egg yolks – many were developed to use up all the extra yolks from construction projects. – WTF Fun Facts
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WTF Fun Fact – Underground Church
A mysterious underground structure found in Russia near the Naryn-Kala citadel was identified as one of the oldest churches on Earth. – WTF Fun Facts
Source: https://www.mdpi.com/2076-3417/9/10/2040