Philadelphia preservationists have taken a wrecking ball to the gut in recent days, with the Boyd Theatre currently coming down and the fate of the legendary Blue Horizon sealed by the Philadelphia Historical Commission’s choice to not designate its interior. Meanwhile, just up North Broad Street, Temple University is in the midst of a demolition spree, in some cases with no plans to replace what it’s knocking down. Rachel Hildebrandt surveys what’s been lost through almost 70 years of campus expansion