Abraham Isaac Kook (1865-1935) is known in Hebrew as HaRav Avraham Yitzchak HaCohen Kook, and by the acronym HaRaAYaH.
The first official Ashkenazi Chief Rabbi of then British-controlled Palestine (a position which was later succeeded by that of Chief Rabbi of Israel), he established the foundation of the Chief Rabbinate of Israel, the Rabbanut, and Israel's national rabbinical courts, Batei Din, that work in co-ordination with the Israeli government, having jurisdiction over much law relating to marriage, divorce, conversion, and education.
He built bridges of communication and political alliances between the secular Jewish Zionist leadership and believers of Religious Zionism. He believed, according to his theological system, that the youthful, secular and even anti-religious Labor Zionist pioneers halutzim were actually part of a grand divine scheme whereby the land and people of Israel were finally being redeemed from the 2,000 year exile (galut) by all manner of Jews who sacrificed themselves for the cause of building up the physical land, as laying the groundwork for the ultimate spiritual messianic redemption of world Jewry.
His empathy towards the anti-religious elements aroused the suspicions of his more traditionalist haredi opponents, particularly that of the old-time rabbinical establishment that had functioned from the time of Turkey's control of greater Palestine, whose paramount leader was Rabbi Yosef Chaim Sonnenfeld, Rabbi Kook's greatest rabbinical rival.
In Rav Kook's thought, the topic of Kodesh and Chol (sacred and profane) plays an extremely important role. Kodesh is the inner taam (taste or reason) of reality - it is the meaning of existence; Chol is that which is detached from Kodesh and is thus neutral, without any meaning. Judaism is the vehicle whereby we sanctify our lives, and “attach all the practical, secular elements of life to spiritual goals which reflect the absolute meaning of existence - God Himself..” 
In March of 1924 he made his first visit to America to attend a “Zionist Conference” held in New York that year.
The Rabbi Kook Museum is
Sources: Israel Ministry of Tourism