President Ulysses S. Grant laid its cornerstone back in 1876. And it's been nothing but spotlight from there for Washington's most prestigious synagogue.

President Obama made history Friday by speaking at Adas Israel, one of the oldest congregations in the city.

“The people of Israel must always know America has its back," he said.

But Obama is far from the only political leader to grace its marbled, tree-lined steps.

As The Washington Post's Juliet Eilperin points out, in 1963 the Rev. Martin Luther King Jr. chose Adas Israel to make his first civil rights speech to a Jewish congregation. Almost every Israeli ambassador to the United States in recent memory has joined the congregation. Top advisers for the secretary of state and Treasury Department worship there. At least two Supreme Court justices drop by on holidays.

"The president is probably the last person in the White House who hasn't been to Adas," Norman Eisen, Obama's former ambassador to the Czech Republic, told Eilperin.

Here's a look at where Washington's Jewish elite worship.

It practices a more modern faith, but it didn't start out that way

Adas Israel bills itself as the largest synagogue in Washington that practices Conservative Judaism, which evolved in the early 1900s as a more modern approach to the religion: Men and women can sit together, and eating kosher food is not a requirement. Conservative Judaism is the second-largest sector of the religion in America, according to a 2013 Pew Research Center survey and a 2014 national Jewish population survey by Berman Jewish DataBank.

But Adas Israel was originally founded in 1869 by a handful of Jewish families who resigned from the only synagogue in D.C. at the time because they wanted a more traditional practice.

Today, Washington has one of the nation's highest percentage of Jewish worshipers, at about 4.3 percent compared with 2 percent of Americans overall, according to the Berman Jewish DataBank.

Many of those are members of Congress: A 2014 Pew Religion study found about 5 percent of Congress is Jewish, more than double the national average. And many of those lawmakers attend Adas Israel.

Its rabbi made headlines last year by coming out as gay

Last year, Adas Israel's senior rabbi Gil Steinlauf sent a letter out of the blue to his congregation and supporters. One of his congregants, Atlantic senior writer Jeffrey Goldberg, shared it with his readers:

I am writing to share with you that after twenty years of marriage, my wife Batya and I have decided to divorce. We have arrived at this heartbreaking decision because I have come to understand that I am gay.

Steinlauf's announcement was well received among the global Conservative branch, which at the end of 2006 controversially announced homosexuality no longer ran afoul of Jewish law.

"There is no need for this sort of secret anymore," Goldberg wrote. "There is no reason for the rabbi of a progressive synagogue to hide from his congregants who he, in fact, is."

It's become the de facto synagogue for politicians to give a nod to Israel

When the prime minister of Israel was assassinated in 1995, then-Vice President Al Gore and members of Bill Clinton's Cabinet and Supreme Court attended a memorial service at Adas Israel.

Presidents from Lyndon Johnson to Richard Nixon have addressed the powerful U.S.-Israeli community there.

Today, U.S.-Israel political relations are at some of their lowest in recent memory. Obama and Israeli Prime Minister Benjamin Netanyahu don't get along, and their distrust was punctuated earlier this year by Netanyahu's joint address to Congress denouncing Obama's nuclear deal with Iran.

That could explain why Obama spoke at Adas Israel on Friday. His administration is at a pivotal moment for the high-profile nuclear negotiations, which is being closely watched by wary members of Congress from both parties. As Eilperin notes, Obama could certainly use the support from the progressive American Jewish community that worships at Washington's most elite synagogue.

[This post has been updated with additional data from Pew Research Center to reflect Conservative Judaism's popularity in America.]