Actually, 2500/18 is only 139kg. That’s a lot, but it’s less than what some people do today

edit for those taking this serious: that block is way heavier than 2.5 tonne. Sandstone has a density of about 2.323 tonne/m3. This block looks about 8 meters long, so 8x8x8x2.323=1.187 kilotonnes