Answer to Puzzle Contest:

Gibraltar. Gibraltar is an invincible fortress or stronghold, Strait (straight) of Gibraltar, Rock (stone) of Gibraltar; insofar as being a stronghold "in the first instance" cannot be penetrated because it is invincible. Take off the first 4 letters and you have an altar, which is commonly used in religious services.

Winner: Tatiana Elorin Achiad

Contest Statistics: Newsletter sent to 302769 subscribers, 22 answers submitted, 19 answers correct, 86.36% accuracy. Chance of a correct answer winning: 5.26%.