The Arabian Peninsula is surrounded by seismically highly active plate margins, while the interior seems to be free from destructive earthquakes. We report two historical earthquakes in Qalhat, Oman, >300 km from any plate boundary and provide archaeoseismological analysis of ruined buildings. The first quake hit the city in 1497 AD with an intensity VII at most; the community survived and damage was repaired. The second event caused total devastation (intensity X-XI), sometime between 1580 and 1592. The city never recovered from the latter; it has been a field of ruins ever since. ShakeMap modeling yielded magnitude Mw 5.5 for the first and Mw 6.5–7.0 for the second earthquake. We suggest that the strike-slip Tiwi Fault or the reverse Qalhat Fault caused the first, while the reverse Qalhat Fault might have caused the second earthquake.