Most home runs by park and city.

Minimum 250 home runs (HR) per park.  Harmon Killebrew was close with 246 in his Minneapolis park, Metropolitan Stadium.  In Fenway Park Boston: Ted Williams 248, Carl Yastrzemski 237 .  But the champ in both categories was New York Giant Mel Ott.

player	HR	AB	park	city	AB/HR
Mel Ott	323	4,576	Polo Grounds	New York	14.17
Sammy Sosa	293	3,475	Wrigley Field	Chicago	11.86
Ernie Banks	290	4,734	Wrigley Field	Chicago	16.32
Mickey Mantle	266	3,970	Yankee Stadium	New York	14.92
Mike Schmidt	265	4,020	Veterans Stadium	Philadelphia	15.17
Babe Ruth	259	2,835	Yankee Stadium	New York	10.95
Stan Musial	252	5,401	Sportsman Park	St. Louis	21.43
Lou Gehrig	251	3,861	Yankee Stadium	New York	15.38

player	HR	AB	parks	city	AB/HR
Mel Ott	348	5,283	Polo/Ebbets	New York	15.18
Babe Ruth	344	3,589	Polo/Yankee	New York	10.43
Sammy Sosa	312	4,032	Com1/Com2/Wrigley	Chicago	12.92
Ernie Banks	290	4,734	Wrigley Field	Chicago	16.32
Mickey Mantle	266	3,970	Yankee Stadium	New York	14.92
Mike Schmidt	265	4,020	Veterans Stadium	Philadelphia	15.17
Stan Musial	252	5,401	Sportsman Park	St. Louis	21.43
Lou Gehrig	251	3,861	Yankee Stadium	New York	15.38

Goudey 1933 card
via Wikimedia Commons

I derived this from baseball-reference.com but had to do it by checking parks and individuals.  I could not run a general database query.  I quickly eliminated HR leaders.

Barry Bonds split time between Pittsburgh and San Francisco, where he played in two parks.

Hank Aaron played all but his final two seasons with the Braves but they moved from Milwaukee to Atlanta.

Willie Mays had a similar experience with his Giants.

Other career HR leaders played for multiple teams and/or in multiple parks.  I looked for obvious candidates.  Did I miss anyone?