The original Iglesia de Santo Domingo (Avenida A and Calle 3 Oeste) was built in the 17th century, but it burned twice and was not rebuilt after the fire of 1756. But it remains famous for one thing that survived, seemingly miraculously: the nearly flat arch (Arco Chato).
Since it was built without a keystone and had almost no curve to it, it should have been a very precarious structure, yet it remained intact even as everything around it fell into ruins. One of the reasons a transoceanic canal was built in Panama [1] was that engineers concluded from the intact arch that Panama was not subject to the kinds of devastating earthquakes that afflict its Central American neighbors.
On the evening of November 7, 2003, just four days after Panama celebrated its first centennial as a country, the arch finally collapsed into rubble. Predictably, attempts to find someone to blame for its neglect—it had been left exposed to the sun, rain, and rumbling traffic of Panama for ages—began almost before the dust settled.
It has since been rebuilt, but its main appeal, its gravity-defying properties through the centuries, can never be restored. The church itself is undergoing a slow restoration.
Links:
[1] http://www.moon.com/destinations/panama